JP2999599B2 - Color recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a color recording device. For example, the present invention is applied to a printer of a digital copying machine or a digital color copying machine.

[0002]

2. Description of the Related Art As a method of transmitting a driving force to each photosensitive drum by a driving motor, there is a method in which a driving force is sequentially transmitted from an end photosensitive drum. In this type, as the transmission distance becomes longer, the manufacturing error of each transmission element accumulates, so that the angle transmission error increases. That is, a large rotation error occurs in the photosensitive drum far from the drive motor. As a result, there is a problem in that a position shift occurs in the image on the photosensitive drum, and a color shift occurs in the image superimposed on the recording paper, thereby deteriorating the image quality.

In order to solve this problem, for example, a "color recording apparatus" has been proposed in Japanese Patent Application Laid-Open No. 2-157868. In this publication, a plurality of photosensitive drums rotationally driven by a single drive motor are juxtaposed to form a color-separated image on each photosensitive drum, and this is printed on a recording paper. In a color recording apparatus for successively superimposing and transferring a color image, the driving motor is installed at a position substantially closest to the photosensitive drum in an intermediate portion. However, this method uses a belt or gear to drive the photosensitive drums, and has a drawback that even if the arrangement of the drive motors is optimized, rotational errors and phase shifts of a plurality of photosensitive drums cannot be eliminated in terms of mechanical accuracy. Therefore, the color overlay accuracy cannot be improved very much.

As described above, among the technical issues for improving the quality of a color hard copy, the color superposition accuracy of each toner of Y (yellow), M (magenta), C (cyan), and BK (black), and sub-scanning Improving the driving accuracy in the direction has become an important issue. In the conventional method using a plurality of photosensitive drums, the color overlay accuracy is limited to about 150 μm due to variations in the scanning position of the writing beam and variations in the transfer position. This factor is caused by variations in the precision of the mechanical elements and variations in electrical timing such as writing start and transfer start. The driving mechanism in the sub-scanning direction has conventionally used a transmission mechanism such as a gear and a timing belt. As the recording density increases, density unevenness (banding) occurs in the sub-scanning direction, and the image quality is hindered. It has become.

The main cause of this problem is the eccentricity or tooth profile caused by the machining error of the gears and pulleys due to the reduction mechanism, and
Error, a transmission error occurs due to a change in the contact ratio, and as a result, pitch unevenness between scanning lines occurs.The density increases in a portion where the pitch is narrow, and the density decreases in a portion where the pitch is wide. This is because density unevenness having a certain period is seen.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple structure of a drive system for a photosensitive drum and a transfer drum, and reduces color timing accuracy by reducing factors of electrical timing errors. In addition, in the transfer paper wrapping mode, using an ironing roller to improve the adhesion between the dielectric film and the transfer paper to improve the color overlay accuracy, and furthermore, the rolling by the magnetic attraction of the magnet ring The purpose of the present invention is to provide a color recording apparatus which improves the accuracy and reliability by preventing transmission of toner on a contact surface by using transmission and realizes high quality of an output image without banding. It is.

[0007]

To achieve the above object, the present invention provides (1)
A transfer drum that has a photosensitive drum and a transfer drum, and is formed on a transfer paper that is electrostatically attracted and wound on the transfer drum from a color-separated image signal that is separated into each color on the photosensitive drum. Planetary roller for directly driving the photosensitive drum in an electrophotographic color recording apparatus in which the transferred toner image is sequentially superimposed and transferred at a contact position between the photosensitive drum and the transfer drum to obtain a color image. A DC servomotor with a speed reducer, two spacing rings as magnet rings fixed to drive shafts on both sides of the photosensitive drum, and magnetic material frames provided on both sides of the transfer drum; Rolling transmission is performed while the gap between the photosensitive drum and the transfer drum is kept constant, and the rolling transmission allows one motor to control both the photosensitive drum and the transfer drum. Performing the rotation driving, further, (2)
Providing a blade and a detector for detecting the home position on the transfer drum side, and controlling the timing of writing and transfer based on the home position pulse of the transfer drum, or (3) controlling the photosensitive drum and the transfer drum A toner image formed from a color-separated image signal of each color on the photosensitive drum on a transfer paper wound electrostatically on the transfer drum and wound on the photosensitive drum. In an electrophotographic color recording apparatus in which a color image is obtained by successively superimposing and transferring a color at a contact position between a drum and the transfer drum, a DC servomotor with a planetary roller speed reducer for directly driving the photosensitive drum; Two spacing rings, which are magnet rings fixed to drive shafts on both sides of the photosensitive drum, and magnetic rings provided on both sides of the transfer drum (4) applying a rolling voltage while maintaining a constant gap between the photosensitive drum and the transfer drum, and applying a bias voltage having the same polarity as that of the toner to the interval ring. The above (3)
, An ironing roller is provided immediately before the transfer position,
Fur brushes are provided at both ends of the ironing roller, and the fur brush cleans the circumferential surface of the spacing ring and the frame of the transfer drum, and irons the transfer paper when winding the transfer paper. Things. Hereinafter, a description will be given based on examples of the present invention.

First, FIG. 2 is a block diagram of a digital color copying machine, in which 31 is a scanner unit, 32 is an optical writing unit, 32a is a polygon mirror, 32b is an imaging lens (fθ lens), and 32c is a folding lens. Bending mirror, 33 is a photosensitive drum, 34 is a charger, 35 is a BK (black) developing device, 36 is a C (cyan) developing device, 37 is an M (magenta) developing device, 38 is a Y (yellow) developing device, 39 Is a photosensitive drum cleaner, 40 is a transfer drum, 41 is a transfer drum cleaner, 42 is a transfer charger, 43 is a separation charger, 44 is a separation claw, 45 is a fixing device, 46 is transfer paper,
7 is a clamper and 48 is an ironing roller.

The toner image formed from the color-separated image signals of the respective colors on the photosensitive drum 33 is transferred onto the transfer paper 46 electrostatically attracted and wound on the transfer drum 40. The color image is obtained by sequentially superimposing and transferring the image at the contact position of the transfer drum 33 and the transfer drum 40. The transfer paper 46 fed from the paper feeding unit is transferred to the clamper 4 on the transfer drum 40.
7 (corresponding to 23 in FIG. 6), the tip is gripped, electrostatically attracted onto the dielectric film 13 by the transfer charger 42 and wound. At this time, the winding step is performed in a state where the photosensitive drum 33 and the transfer drum 40 are in contact with each other. However, in one-turn winding, the adhesion between the dielectric film 13 and the transfer paper 46 may be incomplete. Then, exposure,
After the development, in the step of transferring the toner image formed on the photosensitive drum 33 to the transfer paper 46, transfer defects such as white spots or image blur occur.

When four color toner images are transferred in an overlapping manner, a difference in the amount of color misregistration is observed depending on the presence or absence of an ironing mechanism. In particular, a large color shift occurs during the transfer from the first color to the second color, and the third and subsequent colors tend to be overlaid at the position of the second color. This is because the adhesion between the dielectric film 13 of the transfer drum 40 and the transfer paper 46 is stabilized as the transfer process is repeated. By paying attention to this point, in the transfer paper winding step, the ironing roller 48 is arranged between the position of the clamper 47 and the transfer position so that the ironing roller 48 and the transfer drum 40 are in contact only during the winding step. It is preferable to provide a contact / separation mechanism.

FIGS. 1 (a) and 1 (b) are structural views for explaining an embodiment of a color recording apparatus according to the present invention.
FIG. 3 is a configuration diagram of a photosensitive drum and a transfer drum driving unit shown in FIG. Figure (a) is a plan view, Figure (b) is a side view,
1 is a DC servo motor with a planetary roller reduction gear, 2 is a coupling, 3 is an HP (home position) signal plate, 4 is a photo interrupter, 5 and 7 are interval rings, and 6 is a photosensitive drum (corresponding to 33 in FIG. 2). ), 8 and 10 are bearings, 9 is a drum shaft, 11 is a rotating shaft, 12 is a connecting stay, 13 is a dielectric film, 14 is a frame, 15 is a transfer drum (corresponding to 40 in FIG. 2), and 16 is a control unit. , 17 is a driver, 18 is a spring,
19 is a swing lever, 20 is an eccentric cam, 21 is a motor, 2
2 is a rotation axis.

The photosensitive drum 6 is fixed to a drum shaft 9,
On both sides of the photosensitive drum 6, two spacing rings 5, 7 are axially fixed so as to be concentric with the drum shaft 9. Spacing ring 5,
Reference numeral 7 denotes a magnet ring made of a magnet material such as ferrite. The transfer drum 15 includes a frame 14 made of a ring-shaped magnetic material at both ends, a connecting stay 12 connecting the frame 14, and a rotating shaft 11, and a dielectric film 13 is attached to the surface of the frame 14 in a cylindrical shape. The transfer charger 42 is disposed inside. In addition, the connecting stay 12 includes
A clamper mechanism for clamping the leading edge of the transfer paper is provided.
The rotational drive of the transfer drum 15 performs rolling transmission by the attraction force to the frame 14 due to the magnetic force of the spacing rings 5 and 7 on the photosensitive drum 6 side.

An HP detection plate 3 for detecting the home position is fixed to the rotating shaft 11 of the transfer drum 15, and a home position signal is obtained by turning off a sensor such as the photo interrupter 4. In the driving method of the present invention, since the rolling transmission force is generated by the attraction force of the magnet rings 5 and 7, the positional relationship between the photosensitive drum 6 and the transfer drum 15 may be shifted due to abnormal overload. Further, even if the color misregistration amount of each color within one page is within the allowable value, the running position of the photosensitive drum 6 and the transfer drum 15 is greatly displaced when running for several hundred sheets, and There is a problem that the recording position is shifted.

In order to solve this problem, the home position sensor 3 conventionally provided on the photosensitive drum 6 side is provided on the transfer drum 15 which is the last stage of the drive system.
The problem can be prevented. In other words, if the phase shift between the photosensitive drum 6 and the transfer drum 15 is within an allowable value during one-color recording, the sequence control is performed on the basis of the home position of the transfer drum 15 for each color superposition, so No color shift is accumulated. Further, in the present invention, a contact / separation mechanism between the transfer drum 15 and the photosensitive drum 6 is provided, and the swing lever 19 is urged clockwise by the spring 18 to apply a preload. A large rolling transmission force can be obtained.

Next, another embodiment of the color recording apparatus according to the present invention will be described. First, FIG. 4 is a diagram showing another configuration of the digital color copying machine. In the drawing, 49 is an ironing roller, and the other portions having the same functions as those in FIG. 2 are denoted by the same reference numerals. As in FIG. 2, the photosensitive drum 3 is placed on the transfer paper 46 wound electrostatically on the transfer drum 40.
The color image is obtained by sequentially superimposing toner images formed from color-specific image signals separated into the respective colors on 3 at the contact position between the photosensitive drum 33 and the transfer drum 40 and transferring the toner images. An ironing roller 49 is provided immediately before the transfer position. As shown in FIG. 5, fur brushes 28a and 28b are provided at both ends of the ironing roller.

FIGS. 3A and 3B are diagrams for explaining another embodiment of the color recording apparatus according to the present invention, in which 24 is a solenoid, 25 is a bias voltage, and 26 is an ironing lever. In addition, the same reference numerals are given to portions having the same functions as those in FIGS. 1 (a) and 1 (b). The photosensitive drum 6 is fixed to a drum shaft 9, and two interval rings 5, 7 are axially fixed on both sides of the photosensitive drum 6 so as to be concentric with the drum shaft 9. The spacing rings 5, 7 are magnet rings made of a magnet material such as ferrite. A predetermined bias voltage 25 is applied to the spacing rings 5 and 7 by a DC power supply so as to have the same polarity as the toner. Transfer drum 15
Is a frame 14 made of a ring-shaped magnetic material at both ends,
4, a dielectric stay 13 is attached to the surface of the frame 14 in a cylindrical shape, and a transfer charger 42 is disposed inside. The connecting stay 12 is provided with a clamper mechanism for clamping the leading end of the transfer paper.

When the transfer drum 15 is driven to rotate, the roller is transmitted in a swinging manner by the attraction force of the space rings 5 and 7 on the photosensitive drum 6 side to the frame 14 due to the magnetic force. Therefore, the high-precision rotation of the DC servomotor 1 with the planetary roller reducer can be transmitted to the transfer drum 15 almost. Further, in a state where the photosensitive drum 6 and the transfer drum 15 are in contact with each other, an ironing roller 49 is provided immediately before the transfer position, and the ironing roller 49 is provided at both ends corresponding to the positions of the spacing rings 5 and 7 and the frame 14. Fur brushes 28a and 28b having a large diameter are arranged, and an ironing roller portion 27 having a length corresponding to the width of the transfer paper is provided at the center, and a predetermined friction is applied by a compression spring 29.

The transfer paper winding mode shaft is set in a state where the photosensitive drum 6 and the transfer drum 15 are in contact with each other. The transfer paper, whose leading end is gripped by the clamper 23, is caught when passing through the ironing roller unit 27, thereby receiving a tensile force corresponding to the friction torque toward the rear end, and improving the adhesion with the dielectric film 13. improves. Further, the transfer charger 42
Is applied to the transfer paper and the dielectric film 13.
Is perfect. When a bias voltage having the same polarity as that of the toner is applied to the spacing rings 5 and 7 while the photosensitive drum 6 and the transfer drum 15 are rotating, a bias also acts on the frame 14 of the transfer drum 15 and the fur brushes 28 a and 2.
By rubbing the contact surface with 8b, it is possible to prevent the rotation accuracy from deteriorating due to the adhesion of the toner to be cleaned. Except in the transfer paper winding mode, the ironing roller lever 26 is rotated clockwise by the solenoid 24 to secure an interval with the transfer paper and prevent the color from being distorted during color superposition.

[0019]

As apparent from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: Since the photosensitive drum is directly driven by a DC servomotor with a planetary roller speed reducer, and the transfer drum is rolled and transmitted by the magnetic attraction force of the magnet ring, a conventional belt or the like is used. A high-quality image without banding can be obtained as compared with a driving method using a gear. The photoreceptor drum and the transfer drum can be driven by one motor, and the number of components can be greatly reduced, so that the cost can be reduced. (2) Effects corresponding to claim 2: By disposing a home position sensor on the transfer drum side and using it as a reference pulse for writing timing and transfer timing, color superposition can be performed irrespective of the rotational position of the photosensitive drum. In addition, since relative position deviations corresponding to changes over time can be canceled,
High-precision color overlay can be performed. (3) Effect corresponding to claim 3: By combining a conventional DC servomotor with a planetary roller speed reducer that does not use a speed reduction mechanism such as a belt or gear, and rolling transmission by the magnetic force of a magnet ring, a simple structure is achieved. Accurate driving becomes possible. Also, by applying a bias voltage of the same polarity as the toner to the spacing ring and the frame of the transfer drum,
It is possible to prevent the scattered toner from adhering to the surface and improve the reliability. (4) The effect corresponding to the fourth aspect: the contact between the transfer paper and the ironing roller with the fur brush is brought into contact with the transfer drum to improve the adhesion between the transfer paper and the dielectric film. To prevent. Further, since the adhesion of the toner and dust can be mechanically prevented by the contact of the fur brush, the rotation accuracy can be maintained and a high-quality output image can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a color printing apparatus according to the present invention.

FIG. 2 is a configuration diagram of a digital color copying machine.

FIG. 3 is a diagram showing another embodiment of the color recording apparatus according to the present invention.

FIG. 4 is another configuration diagram of the digital color copying machine.

FIG. 5 is a configuration diagram of an ironing roller.

FIG. 6 is a configuration diagram of a transfer drum.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... DC servo motor with a planetary roller speed reducer, 2 ... Coupling, 3 ... HP (home position) signal board, 4 ... Photo interrupter, 5,7 ... Spacing ring, 6 ... Photoconductor drum, 8,10 ... Bearing, 9: drum shaft, 11: rotating shaft,
12 ... connecting stay, 13 ... dielectric film, 14 ... frame,
15: transfer drum, 16: control unit, 17: dry, 1
8 spring, 19 swing lever, 20 eccentric cam, 21
Motor, 22 ... rotating shaft.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-15663 (JP, A) JP-A-61-87174 (JP, A) JP-A-61-83557 (JP, A) 17668 (JP, A) JP-A-63-109460 (JP, A) JP-A-61-193165 (JP, A) JP-A 1-166059 (JP, A) JP-A 4-233557 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/01 G03G 15/01-15/01 117 G03G 15/16 G03G 21/00 350-352 G03G 21/16

Claims (4)

(57) [Claims] An image forming apparatus comprising: a photosensitive drum and a transfer drum; a transfer sheet electrostatically attracted to and wound on the transfer drum; An electrophotographic color recording apparatus in which a toner image formed from an image signal is sequentially overlapped and transferred at a contact position between the photosensitive drum and the transfer drum to obtain a color image, wherein the photosensitive drum is A direct-drive DC servomotor with a planetary roller reducer, two spacing rings that are magnet rings fixed to the drive shafts on both sides of the photosensitive drum, and magnetic material frames provided on both sides of the transfer drum Rolling transmission is performed while maintaining a constant gap between the photosensitive drum and the transfer drum, and the roller transmission is performed by one motor by the rolling transmission. A color recording device for performing both rotation driving of a ram. 2. The method according to claim 1, wherein a blade and a detector for detecting a home position are provided on the transfer drum side, and timing of writing and transfer is controlled based on a home position pulse of the transfer drum. Color recording device. 3. A color separation device comprising a photosensitive drum and a transfer drum, wherein the transfer paper wound electrostatically on the transfer drum is separated into each color on the photosensitive drum. An electrophotographic color recording apparatus in which a toner image formed from an image signal is sequentially overlapped and transferred at a contact position between the photosensitive drum and the transfer drum to obtain a color image, wherein the photosensitive drum is A direct-drive DC servomotor with a planetary roller reducer, two spacing rings that are magnet rings fixed to the drive shafts on both sides of the photosensitive drum, and magnetic material frames provided on both sides of the transfer drum Rolling transmission while maintaining a constant gap between the photosensitive drum and the transfer drum, and applying a bias voltage having the same polarity as that of the toner to the interval ring. Color recording device. 4. An ironing roller is provided immediately before the transfer position, fur brushes are provided at both ends of the ironing roller, and the fur brush cleans the circumferential surface of the interval ring and the frame of the transfer drum. 4. The ironing of the transfer paper at the time of winding the transfer paper.
The color recording device as described in the above.