JP3315573B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of exposure means around a photoreceptor.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a laser beam printer, a plurality of exposure means are arranged around an electrophotographic photosensitive member (hereinafter simply referred to as "photosensitive member") formed in a drum shape. , Within one rotation of the photoconductor,
There is known an image forming apparatus in which development is repeated a plurality of times to form a plurality of toner images on a photoreceptor and these are transferred onto a transfer material. Examples of a combination of a plurality of toner images formed by the image forming apparatus include a format frame and character information, a black character information and a red mark, a design character and its shading, and the like. Developing with

FIGS. 14A and 14B are schematic views showing an example of an image forming process of such an image forming apparatus. In each of the processes (a) to (f), the upper half shows the charge state of the photoconductor, and the lower half shows the surface potential of the photoconductor at that time.

[0004] In (a) process, the photosensitive member A having a Se photoconductive layer a ₁ to the conductive layer a ₂ in the corona discharger C ₁ to about +
Charge to 600V.

[0005] (b) in the process, performs a first image exposure L ₁ based on image information by the optical information such as format, to form a first electrostatic latent image. At this time, the surface potential is attenuated to about +50 V, for example, in the exposed light portion.

In the process (c), for example, a one-component insulative toner T ₁ having a nonmagnetic positive (+) polarity of red is coated on the developing sleeve. No. 54-43036 (hereinafter referred to as “jumping development”),
Is subjected to reversal development. In the first development, a DC bias voltage of +500 V is superimposed on the alternating voltage and applied to the developing sleeve to perform development.

[0007] In (d) process, by the charger C ₂ to the photosensitive member A surface performing primary charging of the same polarity as the corona discharge. The charger C in the opening of the _second shield multiple grid wires at about 1mm intervals are parallel to stretched and corona discharge wire, and its grid wire bias voltage of + 600V is applied. The distance between the grid wire and the surface of the photoconductor is about 1 mm. Due to this secondary charging, the surface potential of the photoreceptor in the portion to which the red toner T ₁ is applied and in the unexposed portion are both about +60 which is almost the same as the grid bias voltage.
It is charged to 0V.

Next, in a process (e), a second image exposure (scanning exposure) L ₂ is performed to form a second latent image,
Magnetic, for example black in (f) process, performs jumping development with insulating toner T ₂ having the positive polarity was applied to the developing sleeve, the second latent image to reversal development, the second image exposure L ₂ parts forming a black toner T ₂ in. At the time of the second development, the alternating voltage is applied to the developing sleeve by +
Reverse bias development is performed by applying a DC bias voltage of 500 V in a superimposed manner.

Second, at the time of development, the surface potential of the photoreceptor in the red toner developing portion and the unexposed portion becomes about +580 V due to dark attenuation, but the potential of the red toner developing portion is biased to repel the black toner T _2. Thus, color mixing of the black toner with the red toner portion is prevented. Further, a black toner image having high contrast can be obtained.

In this way, a two-color toner image is formed on the photosensitive member A, and the two-color image is formed by transferring the toner image to a transfer material such as paper in a transfer portion.

Next, a schematic configuration of an image forming apparatus using the above-described image forming process will be described with reference to FIG.

[0012] In FIG. 1, 1 is Se photosensitive member as an image bearing member drum which is rotatably supported in the direction of arrow R1, 3 the first charger is first charging means, L ₁
Denotes a first image exposure, 4 denotes a first developing unit as a first developing unit, 6 denotes a charging unit as a _second charging unit, L ₂ denotes a second image exposure, and 7 denotes a second developing unit. Is a second developing device.

With respect to the rotation direction of the photosensitive member 1, the first charger 3, the first developing device 4, the second charger 6, and the second developing device 7 are arranged around the photosensitive member 1 in this order. ing.

First, the procedure for forming a color image will be described. FIG.
, The surface of the photoreceptor 1 is approximately +6 by the first charger 3.
It is charged to 00V. Then, the photosensitive member 1 by a laser beam, a first image exposure based on the format information (scanning exposure) L ₁ is performed. The image exposure L ₁ is a laser light source, an optical modulator, a rotating mirror, is performed in response to an electric signal by an imaging lens (both not shown).

[0015] The first of the first developing unit 4 with a one-component insulating toner T ₁ having the positive polarity of the red of the non-magnetic electrostatic latent image thus obtained to reversal development. The distance between the developing sleeve 41 of the first developing device 4 and the photosensitive member 1 is about 300.
μm, and a bias voltage is applied to the developing sleeve 41 from a power supply. This bias voltage is an alternating voltage, in which a voltage of 1500 Hz and a peak-to-peak voltage V _{PP of} 1500 V (530 Vrms) as an AC component and a voltage of +500 V as a DC component are superimposed.

Next, corona discharge is performed on the surface of the photoreceptor 1 by the second charger 6. A bias voltage of +6.0 kV is applied to the corona discharge wire of the second charger 6 and a bias voltage of +600 V is applied to the grid wire at the shield opening of the second charger 6. Developing portion and an unexposed portion with a red toner T ₁ by the second charging are both charged to about + 600V.

[0017] Next, by image exposure L ₂ corresponding to an electric signal by a laser oscillator (not shown) or the like on the surface of the photosensitive member 1 to form a second latent image based on black print information.

The exposure position of the image exposure L ₂ is set at θ ° downstream of the exposure position of the image exposure L ₁ in the rotation direction of the photosensitive member 1. In this case, in this example, θ is set to 60 °.

[0019] Next, reverse development is performed to a jumping developing the second latent image by the second developing unit 7 having a one-component magnetic toner T ₂ having the positive polarity of the magnetic black. The distance between the developing sleeve 71 of the second developing device 7 and the photoconductor 1 is about 300 μm, and a bias voltage under the same condition as in the first development is applied to the developing sleeve 71 by the power supply.

At the time of the second development, the black toner reciprocates between the developing sleeve 71 and the photoreceptor 1 by the action of the alternating electric field, and the bright portion potential corresponding to the image exposure L ₂ is sufficiently developed. On the other hand, unnecessary black toner does not adhere to the red toner image portion, and the red toner is not scraped off by the black toner. Not, of course the black toner is adhered to the portion which has not undergone image exposure L _2.

FIG. 10 is a sectional view of a driving device of the photosensitive drum 1. Drive gear 1 that rotates integrally with drive motor M
0z, and a photoconductor driving gear 3 that rotates integrally with the photoconductor 1
0z, the photosensitive member 1 has a reduction ratio of 1/3
The motor speed is reduced and transmitted.

[0022]

However, when an image is actually formed by the image forming apparatus having the above-described structure, FIG.
As shown in FIG. 3, a relative displacement occurs between the image using the first exposure and the image using the second exposure. This means that the eccentricity of the drive motor M and the drive gear 10z cannot be eliminated on machining accuracy and assembly accuracy,
When the eccentricity exists, as shown in FIG. 13, the photoconductor speed changes sinusoidally. However, as described above, when the reduction ratio is set to 1/3, the speed of the photoconductor 1 changes. Is 120 °, the phase between the first exposure position and the second exposure position is set to, for example, θ = 60 °.
Images are respectively written in a state shifted by 0 ° (latent images are formed).

Therefore, as shown in FIG. 13, the image using the _first image exposure L ₁ and the image using the second image exposure L ₂ expand and contract in the opposite directions, so that the relative position shift occurs. Appears larger.

As a countermeasure, there is a method of increasing the processing accuracy and the assembling accuracy, and reducing the amplitude (change) of the speed fluctuation. However, there is a limit in practical use, and there is a problem that the cost is high.

In order to avoid the above-described color misregistration, FIG.
As shown in FIG. 2, a direct drive system in which the photoconductor 1 is directly driven by a drive motor M without using a gear has been proposed.

However, when a DC motor is used as the driving motor M, magnetic cogging occurs due to the magnetic pole pitch, and when a stepping motor or an ultrasonic motor is used, speed unevenness occurs at each step angle. Neither of them can lead to a fundamental solution.

Further, as shown in FIG. 11, for example, when the drive power is transmitted by engaging the photoconductor drive gear 30z with the development sleeve drive gear 20z for driving the development sleeves 41 and 71, for example. The relative position shift is further enlarged. The reason is that the developing sleeve drive gear 2
0z and the eccentricity of the developing sleeves 41 and 71 and the processing accuracy are added.
In addition, speed fluctuations due to load fluctuations in one rotation cycle of the toner and the blade (refer to a blade that regulates the toner layer on the developing sleeve) are added, and the amplitude of the above-described photoconductor speed fluctuation (sine wave) further increases. .

As a countermeasure, it is conceivable that the photosensitive member 1 is not driven but is driven separately, but this leads to an increase in the size of the entire image forming apparatus and a complicated structure, resulting in an increase in cost. Not limited to the developing sleeves 41 and 71 described above,
Adjacent units around the photoconductor, for example, a brush roller for a cleaner, a screw for conveying waste toner, a charging roller for primary charging or transfer charging, a screw for conveying and stirring toner in a developing device, and the like are driven from the photoconductor 1 If it cannot be obtained, the configuration of the drive system becomes complicated and the number of parts increases, so that there arises a problem that the cost of parts and assembly increases, and the size of the entire apparatus increases.

Accordingly, the present invention is directed to an image forming apparatus having a plurality of exposure means for forming a latent image, wherein an image is formed so as to eliminate the relative positional shift of a multiplex image without complicating the structure and increasing the size of the apparatus. It is an object to provide a forming apparatus.

[0030]

[0031]

[0032]

The invention according to claim 1 is
Rotate around the axis of rotationA photoreceptor,How to rotate the photoconductor
To form a latent image on the photoreceptorMultiple
Latent image forming means;Rotate using multiple fixed magnetic poles
And rotate the rotation axis.And a driving source.
Image forming apparatus,Formation of two adjacent latent images
The latent image forming position of each means andWith the rotation center of the photoconductor
Is the angle between two straight lines connecting, Next to different polarity
Of each of the two matching magnetic poles and the drive sourceCenter of rotation
Is the angle between two straight lines connecting_M°When  θ_M° × n = θ °(Where n is a natural number)  Set each value so that the relationship of
And features.The invention according to claim 2 is described in claim 1.
In the above image forming apparatus, the driving source is a DC motor.
There is a feature. The invention according to claim 3 is the claim
Item 1. The image forming apparatus according to Item 1, wherein the driving source is a stage.
Characterized in that it is a ping motor.

[0033]

[0034]

[0035][Action] According to the invention of claim 1, At the drive source, the speed
(Such as magnetic cogging)AtMultiple pictures
There is no relative image displacement.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. < Reference Example 1 of the Present Invention > Reference Example 1 of the present invention will be described with reference to FIGS. Note that, of the configuration of the image forming apparatus according to the present invention, the parts that appear in the schematic configuration of FIG.

FIG. 2 is a diagram corresponding to FIG. 10 of the conventional example, and shows a drive train for rotating the photosensitive member 1. A drive gear 13 that rotates integrally with a drive motor (drive source) M, and a drum gear 22 that rotates integrally with the photoconductor 1
And are meshed with a predetermined backlash.
The drive gear 13 and the drum gear 12 constitute a first drive transmission unit. Here, the number of teeth of the drive gear 13 is set to 10 and the number of teeth of the drum gear 12 is set to 60. Around the photoreceptor 1, a latent image forming means for performing a first image exposure L _1, a latent image forming means for the second performing image exposure L ₂ of are provided (both not shown). Also, shown in FIG. 1, respectively of the first exposure position P ₁ and the second and the exposure position P ₂ where the second image exposure L ₂ is made of a first image exposure L ₁ is made, the photosensitive member 1 FIG. 3 shows a change in the speed of the photoconductor 1 and an elongation of an image when an angle θ formed by two straight lines connecting the rotation center C and the rotation center C is 60 ° as in the conventional example.

As described above, one rotation cycle of the speed unevenness due to the mounting accuracy and the processing accuracy of the drive motor M and the drive gear 13 with respect to the drive motor M, the arbitrary point on the surface of the photosensitive member 1 is the second exposure position from the _first exposure position P ₁ to the second exposure position. coincides with the time to move to the exposure position P _2. Therefore, at this time, since the phases of expansion and contraction of the image written by exposure match, there is no relative displacement between the colors on the image. For this reason, even if the gears are eccentric or the mounting accuracy of the drive motor M is set so that the parallelism between the motor shaft of the drive motor M and the rotation center of the photoconductor 1 is shifted, for example, Color shift can be prevented from occurring.

In this embodiment , the reduction ratio between the drive gear 13 and the drum gear 12 is set to 10/60 = 1/6, but it may be 1/12 or 1/24. That is, when the drive motor M rotates an integer, the photosensitive member 1
The above-mentioned effect can be achieved by setting the rotation.

When this is generalized and expressed by an equation, the driving gear 1
3 of the number of teeth Zb, the number of teeth Za of the drum gear 12, the rotational speed of the drive motor M n (where, n is a natural number), a straight line connecting the center of rotation of the first exposure position P ₁ the photosensitive member 1, when also the center of rotation and the angle which the straight line and forms a second line connecting the exposure position P ₂ of the photosensitive member 1 and theta °, can be expressed as (Zb / Za) × n = θ ° / 360 °. This is also applicable, for example, when a step gear 14 is interposed between the drive gear 13A and the drum gear 12A as shown in FIG. Drive gear 13A, drum gear 12A, large tooth portion 15 of step gear 14
a, the number of teeth of each small tooth portion 15b is Zb, Za, Z
where b ′ and Za ′, (Zb / Zb ′) × (Za ′ / Za) × n = θ ° / 36
If the number of teeth is set so as to satisfy 0 °, the above-described effect can be achieved.

In this case, the driving gear 13A and the driving motor M
Since no high accuracy is required for the mounting accuracy and processing accuracy of the step gear 14 and the mounting accuracy and processing accuracy of the step gear 14, a drive system can be realized at low cost. As described above, no matter how many gears are incorporated between the drive gear 13A and the drum gear 12A, the final reduction ratio Zb / Za (Zb,
(Za is an integer) may be set to be equal to θ ° / 360 °.

In this embodiment , the transmission system using gears has been described. However, for example, even in the case of a transmission system using a toothed belt, as long as the above-described equation of the reduction ratio can be satisfied, the present invention is not limited to this. It is possible.

Further, the present invention can be applied to a drive transmission system of a flat belt or a V-belt, or a transmission system of friction drive or magnetic drive. In this case, the reduction ratio determined by the outer diameter ratio of the pulley or the transmission rotating body instead of the gear ratio may be set to a value that satisfies the above equation.

In this embodiment , the exposure positions P ₁ , P ₂
Has been described in two places, but the same applies to three or more places. However, in this case, it is necessary to set the angles θ between the mutually adjacent exposure positions based on the direction along the rotation direction of the photoconductor 1 so as to satisfy the above equations. < Reference Example 2 of the Present Invention > FIGS. 5, 6, and 7 show Reference Example 2 of the present invention. The principle of image formation is the same as in FIG. 14, and the description thereof is omitted here.

FIG. 6 is a longitudinal sectional view showing a schematic configuration of the image forming apparatus of the second embodiment .

In FIG. 1, reference numeral 1 denotes a drum-type Se photoconductor as an image carrier rotatably supported in the direction of arrow R1; 3A, a first charging roller as a first charging means;
₁ a first image exposure, the first developing device 4 is a first developing means, 6 is a second charging unit is a second charging unit, L ₂ is the second image exposure, 7 the first The second developing device is a second developing device. Reference numeral 8 denotes a transfer roller as a transfer unit, 9 denotes a cleaner as a cleaning unit, and 20 denotes a pre-exposure unit which is a charge removing unit on the photosensitive drum. It is arranged in.

The image forming procedure will be described below. Referring to FIG.
Is charged. Then, the photosensitive member 1 by a laser beam, a first image exposure L ₁ based on the first image information. The image exposure L ₁ includes a laser light source, an optical modulator, a rotating mirror, is performed in response to an electric signal by an imaging lens (both not shown). The first of the first developing unit 4 with a one-component insulating toner T ₁ having the positive polarity of the red of the non-magnetic electrostatic latent image thus obtained to reversal development. First
The distance between the developing sleeve 41 of the developing device 4 and the photosensitive member 1 is about 300 μm, and a bias voltage is applied to the developing sleeve 41 by a power supply. This bias voltage is an alternating voltage, and has a frequency of 1500 H as an AC component.
z, a peak-to-peak voltage V _PP A voltage of 1500 V and a voltage of ₊₅₀₀ V as a DC component are superimposed.

Next, a corona discharge is performed on the surface of the photosensitive member 1 by the second charger 6. A bias voltage of +6.0 kV is applied to the corona discharge wire of the second charger 6 and a bias voltage of +600 is applied to the grid wire at the shield opening of the second charger 6. This is the second developing portion and an unexposed portion with a red toner T ₁ by the charging are both charged to about + 600V.

[0049] Next, by image exposure L ₂ corresponding to an electric signal by a laser oscillator (not shown) or the like on the surface of the photosensitive member 1 to form a second latent image based on black print information.

The exposure position P ₁ of the second image exposure L ₂ is
Is set downstream from the first exposure position P ₁ L ₁ of the image exposure L _{1 by} an angle θ ° along the rotation direction of the photoconductor 1 (the direction of the arrow R 1). The angle θ ° is, for example, θ = 60
°.

Next, the reversal development carried out jumping developing the second latent image by the second developing unit 7 having a one-component magnetic toner T ₂ having the positive polarity of the magnetic black. The distance between the developing sleeve 71 of the second developing device 7 and the photoconductor 1 is about 300 μm, and a bias voltage under the same condition as in the first development is applied to the developing sleeve 71 by the power supply.

At the time of the second development, by the action of the alternating electric field,
Black toner between the developing sleeve 71 and the photosensitive member 1 to reciprocate, the light portion potential corresponding to image exposure L ₂ is sufficiently developed.
On the other hand, unnecessary black toner does not adhere to the red toner image portion, and the red toner is not scraped off by the black toner. Never, of course, black toner adheres to the portion not subjected to image exposure L _2.

The red-black multiplex image thus formed is
The image is transferred by the transfer roller 8 onto the transfer material conveyed from the registration roller pair 21 in synchronization with the image by a synchronization unit (not shown). The voltage applied to the transfer roller 8 at this time is several hundred volts. Thereafter, the transfer material is sent to a fixing device (not shown) by the transport unit 22 and is discharged outside the image forming apparatus main body after the toner image on the surface is fixed. On the other hand, the transfer residual toner remaining on the surface of the photoconductor 1 without being transferred to the transfer material moves to the cleaner 9, where the cleaning blade 92 and the cleaning auxiliary roller 91
And transported to a waste toner collecting section (not shown). Further, the photoconductor 1 cleaned by the cleaner 9
After the surface charge is removed by the pre-exposure 20, the next image formation is provided for the next image formation starting from primary charging.

As described above, the rotating members (the charging roller 3 A, the developing sleeves 41 and 71, the transfer roller 8, and the cleaning auxiliary roller 91) that rotate substantially in synchronization with the period of the photosensitive member 1 Etc.).
For example, as shown in FIG. 7, the driving force of these rotating bodies can be obtained by the driven gear groups 3Aa, 41a, 71a, 8a, 9a directly meshing with the drum gear 12C integral with the photoreceptor 1, and the configuration is simplest and low. It becomes a costly drive system. The second drive transmission means is constituted by the drum gear 12C and the driven gear group. Here, the number of teeth of each driven gear is Zd, and the number of teeth Zc of the drum gear 12C is (Zd / Zc) × n = θ ° / 360 ° (where n is a natural number). By setting the numbers, the relative positional deviation (color misregistration) of the red and black images occurs even if the processing accuracy and the mounting accuracy of the respective driven gears around the photosensitive member 1 are roughened as shown in the above-described Reference Example 1. do not do. Each unit is 1
It is possible to realize a configuration in which the above-described displacement does not occur even if there is a load fluctuation in the rotation cycle. First Embodiment FIGS. 8 and 9 show a first embodiment. In the present embodiment, as shown in FIG. 8, a drum shaft 11 that rotates integrally with the photoconductor 1 is directly connected to a driving DC brush motor M via a coupling 10. FIG. 9 shows the driving D
The structure of the C brush motor M is shown in a cross section in a direction perpendicular to the rotation axis. The stator 30 is a permanent magnet field, and the rotor 31 is an electromagnet armature. Current is power supply 3
4 is supplied to the armature winding via the brush 33 and the current element 32, and the magnetic field generated by the armature is always maintained in a direction perpendicular to the field magnetic flux regardless of the position of the rotor 31 even when the rotor 31 rotates. I have. The adjacent magnetic pole pitch of the stator 30 is θ _M °.
, The number of poles N is N = 360 ° / θ _M °
Can be represented by The relationship between the magnetic pole pitch θ _M ° and the angle θ between the first exposure position P ₁ and the second exposure position P ₂ is represented by θ _M ° × n = θ ° (where n is a natural number) ) when set to relationship, as in reference examples 1 and 2, the relative positional deviation (in this case between colors can be prevented from occurring ones) caused by the speed fluctuation generated in response to the number of motor poles.

In this embodiment, a DC motor has been described. However, in the case of a stepping motor, the minimum step angle θ _S ° is set to satisfy θ _S ° × n = θ ° (n is a natural number). A similar effect can be expected by setting to.

[0056]

[0057]

[0058]

According to the present invention, even if the speed variation due to the number of poles drive source for direct drive of the photoreceptor, no relative positional shift of the multiple images.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a reference example 1.

Figure 2 illustrates a gear train of the first drive transmission means of the reference example 1.

FIG. 3 is a diagram showing a relationship between a photoconductor rotation angle, a photoconductor speed variation, and image elongation in Reference Example 1.

FIG. 4 shows another gear train in the first drive transmission means of the reference example 1.

5 is a diagram showing a gear train of the second drive transmission means in Reference Example 2.

FIG. 6 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a reference example 2.

FIG. 7 is a diagram showing an engagement state between a drum gear of Reference Example 2 and gears of respective rotating bodies.

FIG. 8 is a perspective view showing a connection relationship between the drive motor and the photosensitive member according to the first embodiment.

FIG. 9 is a longitudinal sectional view showing the configuration of the drive motor according to the first embodiment.

FIG. 10 is a diagram showing a gear train of a first drive transmission unit in the related art.

FIG. 11 is a view showing a meshing state of a conventional drum gear and gears of respective rotating bodies.

FIG. 12 is a diagram showing a conventional connection relationship between a drive motor and a photoconductor.

FIG. 13 is a diagram illustrating a relationship between a conventional photoconductor rotation angle and fluctuations in photoconductor speed and image elongation.

FIGS. 14A to 14F are diagrams illustrating an image forming apparatus;
FIG. 4 is a diagram for explaining an image forming process when charging, exposure, and development are repeated twice.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 photoconductor 3 first charger 3A first charger (rotary member, charging roller) 4 first developing device 6 second charger 7 second developing device 8 rotating member (transfer roller) 9 cleaner 12 , 12A, 12B, 12C Drive transmitting means (drum gear) 13, 13A, 13B Drive transmitting means (drive gear) 14 Drive transmitting means (step gear) 15a Large tooth portion 15b Small tooth portion 41, 71 Rotating body (developing sleeve) 91 Rotating body (cleaning auxiliary roller) 3Aa, 8a, 41a, 71a, 91a Drive transmission means (follower gear group) C Center of rotation L ₁ First image exposure L ₂ Second image exposure P ₁ First exposure position P ₂ Second exposure position θ Angle between two straight lines connecting each of the first exposure position and the second exposure position with the rotation center θ _M Angle between adjacent poles

Claims (3)

(57) [Claims] (1)Rotate around the axis of rotationA photoreceptor,Said
A latent image is provided on the photoreceptor along the rotation direction of the photoreceptor.
FormA plurality of latent image forming means;Multiple magnets fixed
Rotating the rotation axis by using a pole to generate rotationDrive
A power source, and an image forming apparatus comprising:Latent image forming positions of each of two adjacent latent image forming means
And Angle formed by two straight lines connecting the rotation center of the photoconductor
Degree θ °Two adjacent magnetic poles having different polarities
And the drive sourceAngle formed by two straight lines connecting the rotation center
Degree θ_M°When  θ_M° × n = θ °(Where n is a natural number)  An image forming apparatus, wherein each value is set so that the following relationship is established. (2)The drive source is a DC motor; The image forming apparatus according to claim 1, wherein: (3)The driving source is a stepping motor.
, The image forming apparatus according to claim 1, wherein: