JP3481385B2 - Photoconductor drive unit for color electrophotographic apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive member driving apparatus for a color electrophotographic apparatus in which a plurality of photosensitive members are arranged side by side, and a toner image formed on each photosensitive member is sequentially transferred onto a transfer paper to form a full color image. Regarding the device.

[0002]

2. Description of the Related Art As a conventional photosensitive member driving device for a color electrophotographic apparatus of this type, for example, Japanese Patent Laid-Open No. 6-67505 discloses a device using a plurality of photosensitive members to perform deceleration driving by a timing belt. In the second stage, the second stage has a specified reduction ratio n (the drive pulley rotates an integral number of times while the photoconductor moves from the writing position to the transfer position). A configuration is disclosed in which the timing belt has a circumferential length selected from a plurality of values in a range depending on the speed reduction ratio n (the timing belt of the first stage also rotates an integral number of times while the photoconductor moves from the writing position to the transfer position). Has been done. Also, JP-A-63-1196
In Japanese Patent Laid-Open No. 5 (1994), it is configured such that the time required for the photoconductor to move from the writing position to the transfer position is an integral multiple of the drive unevenness cycle of the drive system, and the distance between the photoconductors of the plurality of photoreceptors is the drive unevenness cycle. It is disclosed to be an integral multiple of.

[0003]

By the way, in the case of driving with a timing belt (a toothed belt), the tooth pitch is partially different due to the elongation and bending of the toothed belt over time, or the toothed belt itself. The unevenness of the tooth pitch causes uneven rotation in the drive transmission. This uneven rotation causes color misregistration in a color electrophotographic apparatus that requires accurate positioning and superposition of multiple colors.
There is a problem that it appears in the image. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a photoconductor driving device for a color electrophotographic apparatus, which can prevent color misregistration due to such a toothed belt.

In addition, there is usually an eccentricity error between the rotary shaft and the pitch circle in the pulley, and this eccentricity causes uneven rotation in the case of the drive pulley and the driven pulley, and in the case of the idler pulley, the moving speed of the toothed belt. By giving the speed unevenness, the rotation unevenness of the driven shaft eventually occurs. This rotation unevenness causes a periodic positional shift, and if the phases are different among the four colors, the color shift occurs on the image. SUMMARY OF THE INVENTION It is an object of the present invention to provide a photoconductor driving device for a color electrophotographic apparatus, which can prevent color misregistration caused by such an eccentricity error of a rotary shaft of a pulley or a pitch circle.

[0005]

According to a first aspect of the present invention, there is provided a color electrophotographic apparatus for driving a plurality of photoconductors by a single drive motor. , Transmitting the driving force from the drive motor to each of the photoconductors using a toothed belt,
While the transfer sheet is moved from one of the photosensitive member to the next photoreceptor, pool 1 point on the toothed belt is provided on the shaft of the pulleys or et following photoreceptor having a single photosensitive member axis Move to Li
However, at the same distance from the leading edge of the image on the transfer paper,
The pulley installed on the shaft of the next photoreceptor is the same as the toothed belt.
It is characterized in that the number of teeth of the pulley provided on the shaft of each photoconductor is selected so as to be driven by the helical teeth .

According to the second aspect of the present invention, an idler pulley is arranged between the pulleys provided on the shafts of the respective photoconductors, and the idler pulley is moved by the transfer paper from one photoconductor to the next photoconductor. It is characterized in that the number of teeth is selected so as to rotate an integral number of times in between.

[0007] pertaining to the third aspect, while moving the driven pulley applying a driving force to the toothed belt, a transfer sheet from one of the photosensitive member to the next photoreceptor, teeth to rotate an integer number of times It is characterized by selecting the number .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a schematic configuration of a color electrophotographic apparatus in which a plurality of photoconductors (photoconductors for respective colors) are arranged side by side and a toner image formed on each photoconductor is sequentially transferred onto a transfer paper to form a full-color image is shown in FIG. Shown in. 1Y in the figure, 1
M, 1C, and 1B are photoconductors for yellow (Y), magenta (M), cyan (C), and black (BK), respectively. A developing device 2 and a cleaner 4 are arranged, and each photoconductor 1Y
Toner images of respective colors are formed on 1B. 7 in the figure
Is a transfer belt, which conveys the transfer paper 14 while attracting it electrostatically, and transfers the toner image onto the transfer paper by each color transfer device 6. In the figure, 8 is a drive roller for the transfer belt 7, 9 is a driven roller, 10 is a separation charger for separating the adsorbed transfer paper 14, 11 is a charge removal charger for removing charges remaining on the transfer belt 7, and 12 is transfer. A cleaner for removing the toner adhering to the belt 7 and a pair of registration rollers 13 for sending the transfer paper 14 at the correct timing.

1 and 2 are views showing an embodiment of the present invention. In the figure, 27 is a motor for driving the photoconductors 1Y to 1B, 23 is a drive pulley fixed to the motor 27, 22 is a toothed belt, and 21Y, 21M, 21C and 21B are driven pulleys fixed to the respective photoconductor shafts 20. Is. In addition, reference numerals 24, 25, and 26 in the drawing denote idler pulleys provided between the driven pulleys 21Y and 21B. With this device, 4
The individual photoconductors 1Y to 1B are simultaneously driven to rotate in the same direction by the motor 27 via the toothed belt 22, and the transfer paper is conveyed along the chain line 25 in the figure.

FIG. 3 shows, as an example, the cumulative pitch unevenness of the teeth when unevenness occurs in the pitch of the individual teeth due to dimensional error in the processing step of the toothed belt 22 and elongation over time. Thus, an irregular pitch error occurs in all the teeth in the belt with reference to one point of the teeth. Therefore, in the present embodiment, while the transfer paper is being conveyed from the point A to the point B along the alternate long and short dash line 25 in FIG.
The number of teeth of the driven pulleys 21Y to 21B, the number of teeth of the idler pulleys 24 to 26, and the position thereof are determined so that one point on 2 moves from the point C to the point D via the point E in the figure. According to this structure, at the same position on the image (at the same distance from the front end of the image), all of the four colors Y, M, C, and BK have the photosensitive members 1Y to 1Y.
The drive of B is driven by using the same position (tooth) of the toothed belt 22, and even if the teeth of the toothed belt 22 have pitch unevenness, the image positions are displaced in the same manner for all four colors. It won't shift.

FIG. 4 is a diagram showing the image position deviation between the respective colors on the transfer paper when the photoconductors 1Y to 1B are driven in the configuration of the embodiment of FIG. 1 using the toothed belt as shown in FIG. , (A) shows the case of the configuration of the embodiment of FIG. 1, (B) shows the time when the transfer paper moves between the photoconductors 1Y and 1B and the time when the toothed belt 22 moves between the photoconductors 1Y and 1B. The case where they do not match is shown. In (A), the driven pulley 21 of each color is driven by the same tooth of the toothed belt 22 at the leading end position of the image, and the images at the same position from the leading end of the image thereafter are driven by the same tooth for each color. , C, Bk
The positional deviation of the image between the four colors is the same, and the color deviation does not occur among the four colors. On the other hand, in (B), the transfer paper is the photoconductors 1Y to 1B.
It takes time to move between the photoreceptor belt 1Y and the toothed belt 22.
It takes longer than the time it takes to move between 1B, and the pattern of misalignment shifts as the colors of Y, M, C, and B progress.
This indicates that a maximum S color shift occurs between colors.

FIG. 5 shows the idler pulleys 24 to 24 which cause the positional deviation of the image similarly to the uneven pitch of the toothed belt 22.
26 is a diagram showing a positional deviation of an image due to eccentricity of the drive pulley 23 and a shape error. If it is eccentric, a positional deviation occurs in a sinusoidal shape as shown in the figure, and if it is a shape error, a positional deviation occurs in a random waveform. In either case, the pulleys 23, 24 ...
It has a repetitive waveform for every 26 rotations. (A) is a configuration in which the idler pulley or the drive pulley is rotated an integral number of times during the time when the transfer paper passes between the photoconductors 1Y and 1B, and here , one rotation is performed. Since the idler pulleys 24 to 26 or the drive pulley 23 are at the same rotational position at the leading edge of the image, even if a positional deviation occurs, the color deviation does not occur among the four colors. On the other hand, (B) is a pulley 23, 24-26
Shows the case where the rotation is not an integral number of times, and the case where the positional deviation of each color is shifted for each color, resulting in a color deviation among four colors. In addition, in FIG. 5, for simplification, a single sine wave is shown, but the waveform in which the number of idler pulleys 24 to 26 and the displacement of the drive pulley 23 are combined is an actual waveform. The waveform is the same as that of 24 to 26, which is repeated every one rotation, and the color misregistration can be prevented.

FIG. 6 is a diagram showing a case where the pulleys 23 and 24 to 26 make two revolutions during the time when the transfer paper moves between the photoconductors 1Y to 1B. As in FIG. 5, the positional deviation is between four colors. It shows that it is possible to make them coincide with each other and prevent color misregistration.

[0014]

As described above, the photosensitive member driving device of the color electrophotographic apparatus according to the present invention is configured such that while the transfer paper moves from one photosensitive member to the next, the teeth of the toothed belt are moved. Also the number of teeth of the pulley provided on the shaft of each photoconductor so as to move from one point of the pulley provided on the shaft of one photoconductor to one point at the same angle position of the pulley provided on the shaft of the next photoconductor As a result of selecting Y., Y. M. C. BK. In all four colors, the photoconductor is driven using the same position (tooth) of the toothed belt, and even if there is tooth pitch unevenness, the image position shifts as in all four colors. The effect is not to be.

According to a second aspect of the present invention, there is provided a photoconductor driving device for a color electrophotographic apparatus, in which an idler pulley arranged between pulleys provided on the shaft of each photoconductor moves a transfer paper from one photoconductor to the next photoconductor. Since the number of teeth is selected so that it rotates an integral number of times during the operation, the timing when the transfer sheet passes through each drum and the timing when the periodic positional deviation caused by the eccentricity of the idler pulley are synchronized are the same for all four colors. There is an effect that the position shifts in the cycle / phase and no color shift occurs between the four colors.

Further, according to a third aspect of the present invention, there is provided a photosensitive member driving device for a color electrophotographic apparatus, wherein a drive pulley for applying a driving force to a toothed belt is an integer while a transfer paper moves from one photosensitive member to the next photosensitive member. By selecting the number of teeth to rotate once, the timing of the transfer paper passing through each drum and the timing of the periodic positional deviation caused by the eccentricity of the drive pulley are synchronized, so that all four colors have the same period and phase. There is an effect that the color misregistration does not occur among the four colors.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a photoconductor driving device of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a front view of the same.

FIG. 3 is a diagram showing the cumulative pitch unevenness of the teeth when the pitch of the individual teeth of the toothed belt is uneven.

FIG. 4 is a diagram showing an image positional deviation that occurs between the respective colors on a transfer paper when the photosensitive member is driven by the configuration of the embodiment of FIG. 1 using a toothed belt having uneven tooth pitch.

FIG. 5 is a diagram showing positional deviation of an image due to eccentricity of an idler pulley and a drive pulley and a shape error.

FIG. 6 is a diagram showing a case where an idler pulley and a drive pulley rotate twice during a time when a transfer sheet moves between photoconductors.

FIG. 7 is a schematic configuration diagram of a color electrophotographic apparatus that sequentially transfers toner images formed on a plurality of photoconductors onto a transfer paper to form a full-color image.

[Explanation of symbols]

1Y, 1M, 1C, 1B photoconductor 2 developer 3 charger 4 cleaner 5 optical writing 6 transfer device 7 Transfer belt 8 drive rollers 9 Driven roller 10 Separation Charger 11 Charge removal charger 12 cleaners 13 Registration roller pair 14 Transfer paper 20 photoconductor shaft 21Y, 21M, 21C, 21B Driven pulley 22 Toothed belt 23 Drive pulley 24, 25, 26 idler pulley 27 motor Maximum S color shift

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiya Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Yutaka Shio 10-3 Kitamura, Tottori, Tottori Prefecture Ricoh Microelectronics Co., Ltd. (72) Inventor Tomonori Yabuta 10-3 Kitamura, Tottori City, Tottori Prefecture Ricoh Microelectronics Co., Ltd. (56) Reference JP-A-7-140753 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/01-15/01 117 G03G 15/00 550 G03G 21/00 350

Claims (3)

(57) [Claims] 1. A color electrophotographic apparatus in which a plurality of photoconductors are driven by a single drive motor, the drive force is transmitted from the drive motors to the photoconductors by using a toothed belt, and a transfer sheet is formed. There while moving from one photosensitive body to the next photoreceptor, one point on the toothed belt is provided on the shaft of the pulleys or et following photoreceptor having a single photosensitive member axis <br / > Go to pulleys, the same distance from the image tip end of the transfer sheet
, The pulley provided on the shaft of the next photoconductor is
A photosensitive member driving device for a color electrophotographic apparatus, wherein the number of teeth of a pulley provided on the shaft of each photosensitive member is selected so as to be driven by the same tooth of the attached belt . 2. An idler pulley is arranged between the pulleys provided on the shafts of the respective photoconductors, and the idler pulley is connected to the transfer paper 1
2. The photoconductor driving device of the color electrophotographic apparatus according to claim 1, wherein the number of teeth is selected so that the photoconductor rotates from an integer number of times while moving from one photoconductor to the next photoconductor. 3. The number of teeth of a drive pulley that applies a driving force to the toothed belt is selected such that the transfer paper rotates an integral number of times while the transfer paper moves from one photoconductor to the next photoconductor. The photosensitive member driving device of the color electrophotographic apparatus according to claim 1.