JPH02284180A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of image multilation due to a mechanical shock to a photosensitive body at the time of latent image formation by forming a joining part of a sunctioning member slanted in the direction where the abutting part of the sunctioning member and the photosensitive body is stretched. CONSTITUTION:The leading edge 38a in the carrying direction of the paper (sunctioning member) 38 sunctioned to a transferring drum 52 is slanted in the specified angle of theta against a bus line 92 of the transferring drum 52, and the leading edge 38a is never abutted wholely to the photosensitive body 10 at a transferring position. That is, since the transferring position is not reached at the same time by the leading tip 38a of the paper but is reached sequencially from its edge part 38b. Thus excessive shocking impact is not affected against the photosensitive body 10, and image multilation at the time of latent image formation is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image forming apparatus configured using an electrostatic transfer transfer device.

In an image forming apparatus (hereinafter referred to as a copying machine) that applies the principle of conventional technology xerography, an electrostatic latent image is formed by exposing an image carrier (hereinafter referred to as a photoreceptor) charged in a negative manner to light. This electrostatic latent image is developed with toner to form a toner image, and the toner image is further transferred and fixed onto a transfer material (hereinafter referred to as paper) to obtain a copy. Among these series of steps, full-color copying becomes possible by performing latent image formation, development, and transfer for each color component on the same sheet of paper. By the way, in the process of performing multiple transfers on the same sheet of paper, conventionally, the leading edge of the sheet is gripped onto a transfer drum by a mechanical device such as a gripper, and the sheet is moved close to a photoreceptor at the transfer position to perform the transfer. The mainstream was what was done. However, the transferable area on the paper is not limited, the paper can be held from any position on the transfer drum, and the transfer quality is good. An electrostatic transfer transfer method has been developed in which the paper is conveyed by electrostatic adsorption without using a mechanical mechanism such as -, and the transfer is performed while the paper and the photoreceptor are in surface contact with each other.

Regarding the latent image forming process, conventionally the mainstream was an analog method in which the photoreceptor was directly irradiated with document exposure light, but in recent years, the contrast of the document read by a CCD etc. has been converted into a time-series electric signal. A digital method in which a latent image is formed by controlling laser light based on this signal has also come into widespread use. Digital methods are convenient in that they can perform various processing on read images and can be stored in a suitable storage medium.

FIG. 11 shows an example of a conventional full-color copying machine using a digital method. In the image processing section 2, the document is illuminated with an exposure lamp, the reflected light is imaged on the image sensor section, and the shading of the image is resolved into small pixels, and at the same time, it is converted into electrical intensity through photoelectric conversion. This −electrical signal is
After being sent to the image processing/storage unit 4 and subjected to necessary processing such as image editing, processing, transfer, and storage, the image is sent to the laser scanning unit 8 via the image output unit 6 and flashed with a laser beam. An electrostatic latent image is formed on the photoreceptor 10. Around the photoreceptor 10, there are a charger 12, a developer 14 with a yellow developer, a developer 16 with a magenta developer, a developer 18 with a cyan developer, which transports the paper while adsorbing it and brings it to the transfer position. An electrostatic transfer transfer device 22 that performs transfer and a cleaning device 20 that cleans the surface of the photoreceptor are arranged in this order.

The electrostatic transport transfer device 22 includes a transfer drum 24 having the same diameter as the photoreceptor 10 and driven at the same speed, and means for applying an electric field to the transfer drum 24 for paper transport and transfer. As shown in FIG. 12, a developed plan view of the transfer drum 24 seen from the inside, the transfer drum 24 includes a semiconductive resin film 26, a plurality of electrodes 28 provided at regular intervals inside the resin film 26, It is composed of an electrode 28 and a support 30 made of an insulator that supports the resin film 26, and the electric field necessary for sheet conveyance and transfer is generated by, for example, brush power feeding at the position indicated by 32 in the figure. can now be applied.

The paper 38 fed from the paper feed tray 36 by the feed roller 34 is attracted onto the transfer drum 24 to which an electric field for paper attraction is applied, and is moved to the transfer position, that is, the photoreceptor 10.
The yellow toner image is transferred to the position where the transfer drum 24 contacts the yellow toner image. During the second rotation of the transfer drum 24, a magenta toner image is transferred to the paper, and during the third rotation, a cyan toner image is transferred to the paper, and in some cases, a fourth
A black toner image formed on the photoreceptor 10 is transferred to the rotating eye by a black developing device (not shown). The paper on which three to four color multiple transfer images of the same original image have been formed on the transfer drum 24 is transferred to the transfer drum 24 at a predetermined timing.
The sheet is peeled off from the sheet, passes between fixing rollers 40 and 42, and is discharged onto a discharge tray 44.

Problems to be Solved by the Invention Conventionally, when paper is gripped onto a transfer drum by a mechanical mechanism such as a gripper, even if the paper collides with the photoreceptor, the position is not at the leading edge of the paper but at the position where it is gripped. The impact is small because the curved part has an appropriate curvature near the front edge of the paper. Since no curved portion is formed, the impact when the leading edge of the paper collides with the photoreceptor becomes large.

Furthermore, in order to apply a sufficient transfer electric field at the transfer position, the photoreceptor and transfer drum are in contact with each other, so when the paper attracted to the transfer drum reaches the transfer position, the leading edge of the paper, especially if the paper is thick, may come into contact with the photoreceptor and give a large impact, resulting in image disturbance during latent image formation. Further, when the joint of the cylindrically supported resin film reaches the transfer position, a similar impact is applied to the photoreceptor, which may cause image disturbance during latent image formation.

Incidentally, even image disturbance during formation of a latent image due to a slight impact force becomes a particularly serious problem in a digital image forming apparatus. This is because optical writing cannot be performed at a desired position, resulting in skipped images and noticeable local color tone disturbances. This is because in the analog method, the total exposure amount of any minute area on the photoreceptor is given by an integral value defined by the slit width on the optical path and the rotation speed of the photoreceptor, whereas in the digital method, the exposure is made using laser light. This is because writing is performed by one-time optical scanning. In other words, in the digital method, unlike in the analog method, each pixel is exposed to light in a very short time, so even a slight impact can cause significant image disturbance.

In addition, the problem of impact due to the edge of the paper or the seam of the resin film,
This problem occurs not only in an electrostatic cliff transfer device configured using a transfer drum, but also in an electrostatic transfer transfer device configured by supporting a resin film in the form of an endless belt. In other words,
A similar problem occurs in an electrostatic transfer transfer device configured to attract the leading edge of a sheet without using a mechanical mechanism such as a gripper.

The present invention was created in view of such technical problems, and an object of the present invention is to provide an image forming apparatus that is free from the possibility of image disturbance during formation of a latent image due to mechanical impact on a photoreceptor.

Means and Effects for Solving the Problems A photoconductor on which a toner image is formed through a latent image forming process and a developing process, and a leading edge of a sheet of paper onto which the toner image is transferred are immobilized on the outer surface at least at a transfer position. In an image forming apparatus (simply referred to as the "apparatus" in this section) comprising a suction member that moves along a track that contacts the surface of the photoreceptor while electrostatically adsorbing it, the joint of the suction member By forming the contact portion of the suction member and the photoconductor obliquely with respect to the extending direction, the entire joint of the suction member is prevented from contacting the photoconductor, and the impact force is reduced. Image disturbance during latent image formation is prevented.

"In device J, by making the paper stick to the suction member diagonally with respect to the conveying direction, when the paper moves to the transfer position, the leading edge of the paper does not completely collide with the photoreceptor. Since the particles collide gradually from the end of the tip, the impact force on the photoreceptor is reduced, and image disturbance during latent image formation is prevented.

In the "device", by completing the latent image formation on the photoreceptor before the leading edge of the paper adsorbed by the adsorption member reaches the transfer position, even if the photoreceptor receives the impact force of the paper collision, No image disturbance occurs during latent image formation.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a side view of the main parts of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line n-U in FIG. 1, and FIG. 3 is a transfer shown in FIG. 1. FIG. 4, which is a partial perspective view of the drum, is a power supply connection diagram of the brush power feeding device shown in FIG.

In FIG. 1, 10 is a photoreceptor, 52 is a transfer drum disposed so as to be in contact with the surface of the photoreceptor 10 at the transfer position, 54 is a brush power supply device for feeding power to the electrodes of the transfer drum 52, and 34 is a A feed roller that sends out the paper 38 placed on the paper feed tray 36 in the direction of the transfer drum 52, 56 a skew device that tilts the paper 38 sent out by the feed roller 34 by a predetermined angle as described later, and 58 a peeling device. The tip of the transfer drum 5
2, a conveyor belt 60 conveys the paper peeled by the peeler claw 58 in the direction of the fixing device; This is a cleaning blade that is provided so as to be able to move toward and away from the cleaning blade. The cleaning blade 62 is provided to clean the transfer drum 5 when a paper jam occurs.
Even though the paper is not attracted to the transfer drum 5,
This is to remove the toner image transferred to 2.

As shown in FIG. 3, the transfer drum 52 includes a semi-conductive resin film 64, a plurality of band-shaped electrodes 66 provided at regular intervals inside the resin film 64, and each of the electrodes 66 attached to the resin film 64. It is composed of an insulating elastic layer 68 that is fixed, and a rigid drum 70 made of metal or the like that supports these members. Here, the semiconductive resin film 64 is made of a resin such as acrylic, vinyl chloride, polyester, polypropylene, or various rubber containing an appropriate amount of an antistatic agent such as carbon black, and has a volume resistivity of 10' to 1012 Ω. cm, and its thickness is, for example, 0.25 mm. Further, the electrode 66 can be formed on the elastic layer 68 by conventional conductive pattern forming techniques such as etching or screen printing, and has a width of about 0.5+ nm. Regarding the spacing between each electrode, if it is 1 u or more, electrode patterns are likely to occur in the transferred image, so the smaller the spacing, the better; however, if it is too small, secondary problems such as short circuits will occur, so it should be about 0.
．． 5 mm is optimal. The material of the elastic layer 68 is as follows:
An elastic body such as silicone, silicone foam, or EPDM (ethylene propylene rubber) with a hardness of 50° or less is desirable. Hardness of 50° or less is 50
This is because if it is more than 0.0°, it becomes difficult to adjust the contact force between the photoreceptor and the transfer drum to an optimum value within a range that allows obtaining a good transferred image. In FIG. 3, the ends of the resin film 64 are removed to expose the electrodes 66 because power is supplied to each electrode 66 from the outside of the transfer drum 52 by a brush power supply device, which will be described below. It's for a reason.

As shown in FIG. 2, the brush power supply device 54 is provided to cover the exposed electrode portion of the transfer drum 52, and inside the brush power supply device 54, two brushes for power supply for performing various functions are arranged in the circumferential direction. arranged in alternating rows. Brush power supply device 54
The functions of the transfer section 5 differ depending on its position in the circumferential direction, so for convenience, as shown in FIG.
4a, a first conveyance section 54b corresponding to the paper withdrawal position,
The second transport section 54c is inserted upstream of the paper peeling position in the first withdrawal stage.

The power connection of each part of the brush power supply device will be explained with reference to FIG. In addition, in the figure, the brush power supply device 54 is connected to the first conveyance section 54.
This corresponds to a developed plan view broken between the second transport section 54b and the second conveyance section 54c (section A on the first surface). In the transfer section 54a, 72 is a transfer brush, which is connected to the positive side of a transfer power source 76 via a switch 74.
The negative side of is grounded. According to this configuration, a constant voltage can always be supplied to the electrode that has moved to the transfer position as the transfer drum rotates. Transfer brush 72
Auxiliary transfer brushes 78 are provided on both sides of the
By grounding this, the electric field in the transfer section can be stabilized, and good transfer quality can be obtained. That is, since transfer is generally performed by moving charged toner particles on a photoreceptor along lines of electric force that form a transfer electric field, by providing an auxiliary transfer brush, the transfer weight is confined in a narrow space. It is possible to prevent the toner particles from being transferred before they move to the transfer position, and defects such as blurring of the transferred image are less likely to occur. In the first conveyance section 54b, 80 is a first suction brush, which is alternately connected to a switch 82 and a ground section. 84 is a first suction power source provided between the switch 82 and the ground portion. In the second conveyance section 54c, 86
are second suction brushes, which are alternately connected to the changeover switch 88 and the ground portion. The changeover switch 88 switches between connecting the second suction power source 90, which is connected to the negative side or grounded, to the positive side and connecting it to the ground portion.

The operation of the apparatus of this embodiment will be explained below. Transfer drum 5
2 is rotated and the switch 82 is turned on, as the switch 82 rotates, the electrode 66 corresponding to the till feeding section 54b changes to positive, floating, ground, floating,
Since the potential changes repeatedly, an electric field is formed between the electrodes connected to the positive part and the ground part, making it possible to attract paper. When the paper 38 is fed out by the feed roller 34 in this state, the fed paper is tilted at a predetermined angle with respect to the conveyance direction by the skew device 56 and adsorbed onto the transfer drum 52 .

The paper 38 that is obliquely attracted onto the transfer drum 52 is sent to a transfer position as the transfer drum 52 rotates, where the first color toner image is transferred. In this case, as shown in FIG. 5, the leading edge 38a of the paper 38 in the conveying direction that is attracted to the transfer drum 52 is inclined at a predetermined angle θ with respect to the generatrix 92 of the transfer drum 52, so that the leading edge 38a is Since the entire sheet does not come into contact with the photoconductor 10 at the transfer position, in other words, the leading edge 38a of the paper does not reach the transfer position at the same time, but reaches the transfer position sequentially starting from the end 38b, so that excessive impact force is not caused. It does not act on the photoreceptor 10, and image disturbance during latent image formation is prevented. The larger the inclination angle θ, the more remarkable the above effect, but image distortion can be sufficiently prevented even when the inclination angle θ is a few degrees or less. The paper onto which the first color toner image has been transferred is adsorbed by the transfer drum 52 as it is, and then rotates two or three more times to transfer the second and subsequent color toner images. Therefore, at this time, the second conveyance section 54c is also in the paper suction state like the first conveyance section 54b. When the transfer of all the toner images is completed, the switch 88 is switched to the grounding side at a timing earlier than the leading edge of the paper reaches the peeling position, and the suction force in the second conveying section 54c is gradually removed, and the paper is peeled off from the transfer drum 52 by a peeling claw 58, and sent to the next process such as a fixing device by a conveyor belt 60. Here, the reason why the second conveying section 54c is grounded at the above-mentioned timing is because the paper is removed by the peeling claw 5 before the static electricity removal from the resin film is completed with an appropriate time constant.
This is to prevent explosion (a phenomenon in which toner scatters) that occurs when the toner is forcibly peeled off by the method 8.

FIG. 6 is a side view of the main parts of an image forming apparatus showing an embodiment in which a resin film is formed into a belt shape. This device includes a resin film 94 formed in the shape of an endless belt, a pair of rollers 96 and 98 on which the resin film 94 is mounted, and a pair of rollers 96 and 98 disposed on the horizontal surface of the resin film 94, each carrying cyan, magenta, and yellow toners. A cyan photoreceptor 100, a magenta photoreceptor 102, and a yellow photoreceptor 104, on which the same original image is developed, and an elastic body that rotates with each photoreceptor 100, 102, and 104 while sandwiching a resin film 94 therebetween. Roller 106.
108, 110, and a power supply device that supplies a predetermined voltage to an electrode provided inside the resin film 94 at a transfer position where each photoconductor contacts the resin film 94 and a paper transport position other than the transfer position where the flat portion of the resin film is transferred. 112, and a cleaning blade 114 for removing toner undesirably attached to the outer surface of the resin film 94. Incidentally, since the electrical connection of the brush of the power supply device 112 can be made according to FIG. 4, the explanation thereof will be omitted.

In this configuration, when the paper 38 is fed from the paper cassette 36 by the feed roller 34, the leading edge of the paper is detected by a paper feed sensor (not shown), and this detection causes the image to be written on each photoreceptor 100, 102, 104. The timing is determined.

At the same time, a predetermined electric field is applied by the power supply device 112 to the paper transport position and the transfer position. The paper adsorbed to the resin film 94 after being tilted with respect to the paper conveyance direction by the skew device 56 is transferred with a cyan image, a magenta image, and a yellow image, respectively, when passing directly under the photoreceptors 100, 102, and 104. As a result, multiple transfer images for the same image are formed. Images are written on the photoreceptors 100, 102, and 104 sequentially after a delay of the paper transport time, and the three colors are controlled so that they overlap.

The paper on which multiple transfer has been completed is further sent to a fixing device, where fixing is performed.

In a tandem type device constructed using such a belt-shaped resin film, in order to keep the transfer efficiency constant and to prevent hollow characters (a phenomenon of hollow images), the resin is transferred using an elastic roller. Since the film is brought into contact with each photoreceptor, vibration of each photoreceptor can be prevented by tilting the sheet with the skew device 56, as in the previous embodiment, and image disturbances are eliminated.

In the apparatus shown in FIG. 1, if the resin film 64 of the transfer drum 52 cannot be seamlessly formed, as shown in FIG.
Direction 116 in which the contact portion between the resin film 64 and the photoreceptor 10 extends
It is best to form it at an angle. This can prevent the seam 64a of the resin film from shockingly abutting against the photoreceptor 10 or the cleaning blade 62 and causing image disturbance. For example, the step at the seam is 15
At 0 μm, by setting the tilt angle to 5°, image disturbance could be almost completely prevented.

In the apparatus shown on the sixth page, if it is not possible to seamlessly form a belt-shaped resin film, as shown in FIG. Direction 1 in which the contact portion of the body 100) extends
By forming it obliquely with respect to 18, image disturbance can be prevented as in the embodiment shown in FIG. Also,
Generally speaking, in the case of a tandem type, unlike in the case of a drum type (see Figure 1, etc.), the collision between the cleaning blade and the seam of the resin film directly leads to vibration, but by forming the seam diagonally, , it is possible to suppress this vibration and prevent image disturbance.

In the device shown in FIG. 6, the elastic roller 1
By setting the surface hardness of 06, 108, and 110 to be relatively low, it is possible to substantially eliminate the influence when the joints of the resin films come into contact with each photoreceptor.

FIG. 9 is a block diagram of a full-color copying machine showing an embodiment in which image disturbance is prevented by changing the timing of latent image formation.

A rail 124 is arranged in parallel to the document placement glass 122 on the apparatus main body 120, and an optical case 126 is placed on this rail 124.
A light source 128, a mirror 130, and a lens 132. Three solid-state light receiving devices (CCD) 134a, b, and c are provided within the optical case 126. These solid-state light receiving elements 134a, b, and c are arranged in parallel on a base 136 at regular intervals, as shown in FIG.
A blue filter 138a, a green filter 138b, and a red filter 138c are provided on each light receiving surface. For this reason, the optical case 126 is moved back and forth by a drive mechanism (not shown) and is placed on the document placement glass 122.
When the colored original 140 is subjected to slit exposure, the blue component of the color image original passes through the blue filter 138a to the solid-state light receiving element 134a, the green component passes through the green filter 138b to the solid-state light receiving element 134b, and the red component passes through the red filter 138C. The light is manually applied to the solid-state light receiving element 134c via the light receiving element 134c. The output of each solid state light receiving element 134a, b, c is
buffer memory 144a via leads 142a, b, c, respectively.

It is supplied and stored in b and c. These buffer memories 144
Image signals from a, b, and c are selectively supplied to the semiconductor laser 146 by a switching mechanism (not shown). The semiconductor laser 146 controls the laser beam based on the input signal, scans this laser beam with the scanning member 148, and scans the laser beam with the lens 1.
50, the photoreceptor 10 is irradiated via the mirror 152 to form an electrostatic latent image. And buffer memo this electrostatic latent image! Developing is performed using a developer corresponding to the output signals of J144a, b, and c. Note that other parts such as the developing process are constructed in the same manner as in FIG. 11 or FIG. 1.

In a full-color copying machine having such a configuration, by setting the length l from the laser beam irradiation position to the transfer position on the outer circumferential portion of the photoreceptor 10 to be larger than the length in the electrical feeding direction of the paper, Since the formation of a latent image on the photoreceptor 10 can be completed before the leading edge of the paper adsorbed to the resin film of the transfer drum 22 reaches the transfer position, even if the leading edge of the paper collides with the photoreceptor 10, , image disturbance does not occur due to the impact force.

In the above embodiment, each electrode is alternately connected to a positive voltage B (for example, +1500 V) and a grounding section in order to apply an electric field for adsorption to the paper transport section. One side does not need to be the grounding part. That is,
High voltage and low voltage mean relatively + (plus) side voltage and relatively - (minus) side voltage. Therefore, specific combinations of high voltage and low voltage include +2000V and +500V, +1500V and OV1+
1000V and -500V, OV and -1500V.

There are -500V and -2000V, etc.

Effects of the Invention As described in detail above, the configuration of the present invention has the effect that it is possible to provide an image forming apparatus that is free from image disturbance caused by mechanical impact on the photoreceptor.

[Brief explanation of drawings]

FIG. 1 is a side view of the main parts of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a transfer shown in FIG. 1. FIG. 4 is a power supply connection diagram of the brush power supply device shown in FIG. 1; FIG. 5 is a diagram for explaining how paper is obliquely attracted to the transfer drum; FIG. 6 is a partial perspective view of the drum; 7 is a side view of the main parts of an image forming apparatus showing another embodiment of the present invention; FIG. 7 is a diagram for explaining how the resin film seam of the apparatus shown in FIG. 8 is a diagram for explaining how the joints of the resin films of the apparatus shown in FIG. 6 are formed diagonally, and FIG. 9 is a block diagram of a full-color copying machine showing still another embodiment of the present invention. FIG. 10 is a perspective view of the solid-state photodetector shown in FIG. 9, and FIGS. 11 and 12 are diagrams for explaining the prior art. 10.100,102,104...photoreceptor, 22...
- Electrostatic transport transfer device, 24.52...Transfer drum, 26.64.94...Resin film. Applicant: Fuji Xerox Co., Ltd. Agent: Patent Attorney Takashi Matsumoto Figure 1 Figure 2 Figure 2 Figure b Figure 11 Figure 10 Figure 12

Claims (3)

[Claims] (1) A photoconductor, on whose surface a toner image is formed through a latent image formation process and a development process, and the photoconductor, while the leading edge of the paper onto which the toner image is transferred is electrostatically attracted to the outer surface at least at the transfer position. In an image forming apparatus including an adsorption member that moves along a track that contacts a surface of a body, a joint of the adsorption member extends from a contact portion between the adsorption member and the photoreceptor. An image forming apparatus characterized by being formed obliquely with respect to a direction. (2) A photoconductor, on whose surface a toner image is formed through a latent image formation process and a development process, and the photoconductor, while the leading edge of the paper onto which the toner image is transferred is electrostatically attracted to the outer surface at least at the transfer position. An image forming apparatus comprising a suction member that moves along a track that contacts the surface of a body, characterized in that the suction member suctions the paper diagonally with respect to the conveyance direction thereof. image forming apparatus. (3) A photoconductor on whose surface a toner image is formed through a latent image forming process and a developing process, and the photoconductor while electrostatically adsorbing the leading edge of the paper onto which the toner image is transferred to the outer surface at least at the transfer position. In an image forming apparatus that includes an adsorption member that moves along a track that contacts the surface of the body, the photoreceptor moves before the leading edge of the paper adsorbed to the adsorption member reaches the transfer position. An image forming apparatus characterized in that forming a latent image on the image is completed.