JPH11201244A - Belt device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce meandering quantity of a belt without using any special part. SOLUTION: A belt device is provided with the following means: A calculation means for a deflection around of width direction belt positions to detect a deflection amount Bs of width direction belt positions between a width direction belt detecting position B0 and a width direction belt base position Ba of the belt supported by an alignment adjustment roller 27, a determination means for motor rotating position for control of positional holding time rate to determine θi, θi+1 when the rotating position of a stepping motor is made to be θi, which is determined for each one step of rotation from the rotating position θ0 in detection of a detecting position B0, a calculation means for positional holding time rate to calculate positional holding time rate to hold the belt B on the base position Ba, a motor rotational position adjustment signal output means to output holding signals to θi or θi+1 alternately in accordance with the positional holding time rate, and a belt position adjustment device to adjust the tilted angle of a roller shaft 27a of the roller 27 by adjusting the motor rotation position in accordance with the output of the rotational position adjustment signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt drive roll used in copiers, laser printers, and other electrostatographic systems and a plurality of belt supports including an alignment adjustment roll capable of adjusting the direction of a roll axis. The present invention relates to a belt device having a roll (a photoreceptor belt, an intermediate transfer belt, a sheet transport belt, or the like) rotatably supported by a roll and the belt support roll. The present invention relates to a belt device provided with a belt width direction position adjustment device for adjusting a certain belt width direction position.

[0002]

2. Description of the Related Art Conventionally, in order to reduce the fluctuation of the belt position in the belt width direction due to the meandering of the belt of the belt device, the direction of the roll axis of the alignment adjusting roll is changed according to a detection signal of the belt position in the belt width direction. A belt device that performs an alignment adjustment, which is an adjustment, is known, and such a technique for controlling the meandering of the belt is also called active steering. In the active steering for adjusting the inclination of the roll axis of the alignment adjustment roll, in order to suppress the belt meandering to 10 μm or less, an alignment adjustment device (an actuator for adjusting the roll inclination angle) for adjusting a roll alignment adjustment amount (roll inclination angle). ) Requires very high resolution.

When performing roll alignment adjustment using a servomotor for an alignment adjustment device, the position of the roll axis of the alignment adjustment roll cannot be maintained unless the servomotor is energized. For this reason,
For example, when the power of a copying machine or the like is turned off, the position of the alignment adjustment roll changes due to its own weight, and the adjusted roll alignment may be out of order. When the power is turned on next and the copying is started, the meandering of the belt is large, and it takes a long time until the roll alignment is again properly adjusted. During that time, the printed image becomes distorted, and in the case of a color copier, a color shift occurs. Also,
If the position change of the alignment adjustment roll is large, it may interfere with other components in the device and cause a failure or the like.

On the other hand, when a stepping motor is used as an actuator (alignment adjusting device), the position of the alignment adjusting roll changes even when the power is turned off because the stepping motor has a certain holding force even when the power is not supplied. In other words, the belt can travel without meandering the next time the power is turned on next time. However, in order to suppress the meandering amount of the belt to less than tens of μm, the adjustment amount of the alignment adjusting roll should be 50 to 50 μm.
It is necessary to control within an error range of 80 μm. For this reason,
It is necessary to adjust the direction of the roll axis of the alignment adjustment roll with high resolution.

Therefore, microsteps are sometimes used to increase the resolution. The following technology (J01) is known as a conventional technology using a microstep for driving a photoconductor and an endless belt. (J01) Technology described in JP-A-8-137362 The technology described in this publication uses a microstep for driving a photoconductor and an endless belt. However, when five-phase microsteps are used, the resolution increases five times, but the driver for controlling the motor becomes expensive.

[0006] The use of a worm gear to improve accuracy is not suitable because the worm gear is expensive. Further, conventionally, the following technique (J02) has been known which achieves the same effect as adjusting the direction (inclination angle) of the roll axis of the alignment adjustment roll to an arbitrary position within the adjustment range. (J02) Technology described in JP-A-6-87566 The technology described in this publication holds the orientation (inclination angle) of the roll axis of the alignment adjustment roll in one of both ends of the adjustment range, and It describes a method of arbitrarily setting the average value of the axial position of the belt by adjusting the ratio of the time held at each end (position holding time ratio).

[0007]

[Problems to be solved by the invention]

(Problem of (J01)) However, in the conventional technique (J02), the direction of the roll axis is held at one of both ends of the range of adjustment of the direction of the roll axis. The time required to change the direction of the roll axis from one end to the other end of both ends of the adjustment range of the direction of the roll axis becomes longer. For this reason, the time required for position adjustment in the belt width direction becomes longer, and it is difficult to suppress the meandering amount of the belt to less than tens of μm.

The present invention has been made in view of the above-mentioned circumstances, and an object of the following (O01) is a belt device using a stepping motor as an actuator for driving an alignment adjusting roll for preventing belt meandering. (O01)
To reduce belt meandering without using special parts.

[0009]

Next, a description will be given of the present invention which has solved the above-mentioned problems. In the description of the present invention, reference numerals in parentheses added after constituent elements of the present invention denote constituent elements of the present invention. Reference numerals of corresponding components of the embodiment described later. The reason why the present invention is described in correspondence with the reference numerals of the components of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(Invention) In order to solve the above problems, a belt device of the invention has the following requirements. (A01) The belt drive roll (25) and the roll shaft (27a) A belt (B) rotatably supported by a plurality of belt support rolls (25 to 29) including an alignment adjustment roll (27) capable of adjusting an inclination angle from a reference posture, and (A02) a stepping motor (M2). A belt position adjusting device (Bc) for adjusting the roll axis tilt angle of the alignment adjusting roll (27) by adjusting the rotational position in step units, (A03) in the roll axis direction of the belt supporting rolls (25 to 29); The belt (B)
A width direction belt position sensor (SNb) for detecting the width direction belt position which is the position of the width direction belt detection position B0 and the width direction belt reference position Ba detected by the width direction belt position sensor (SNb). A width direction belt position shift amount calculating means (C2) for detecting the width direction belt position shift amount Bs (= Ba-B0) which is the position shift amount of the width direction belt position shift amount Bs (= Ba-B0) Motor rotation position adjustment signal output means (C6) for outputting a rotation position adjustment signal of the stepping motor (M2) for adjusting the roll shaft inclination angle in accordance with the following conditions: Θa is the rotational position of the stepping motor (M2) for holding the belt, and the width direction belt detection position B is
The rotation position of the stepping motor upon detection of 0 is θ0, the rotation amount of one step of the stepping motor (M2) is Δθ,
1 in a fixed direction from the stepping motor rotation position θ0
The motor rotation position determined every time the step rotates is defined as θi (i
= 0, 1, 2,...), The Bs (= Ba−B
0) Motor rotation adjustment amount θs (= θa−θ0) determined according to 0)
Is θi ≦ θs <θi + 1 (that is, iΔθ ≦ θs
<(I + 1) Δθ) The motor rotation position θ
(A4) Position holding time ratio controlling motor rotation position determining means (C4) for determining i, θi + 1, (A07) The ratio between the time for holding the motor rotation position at θi and the time for holding the motor rotation position at θi + 1. The position holding time ratio, wherein the motor rotation position θ
position holding time ratio calculating means (C5) for calculating the position holding time ratio for holding the belt (B) at the widthwise belt reference position Ba corresponding to a, (A08) the rotational position of the stepping motor (M2) The motor rotation position adjustment signal output means for outputting a motor rotation position adjustment signal for position holding time ratio control for alternately holding the motor rotation position θi or θi + 1 at a time ratio corresponding to the position holding time ratio. C6), (A09) The belt position adjusting device for adjusting the rotational position of the stepping motor (M2) according to the output signal of the motor rotational position adjustment signal output means (C6) in order to adjust the widthwise belt position. (Bc).

(Operation of the Present Invention) Next, the operation of the belt device of the present invention having the above-described features will be described. In the belt device of the present invention having the above-described features, the belt (B) includes the belt driving roll (25) and the alignment adjusting roll (27) capable of adjusting the inclination angle of the roll shaft (27a) from the reference posture. Including a plurality of belt support rolls (25 to 2
It is rotatably supported by 9). The width direction belt position sensor (SNb) is connected to the belt support roll (25 to 2).
9) The width direction belt position, which is the position of the belt (B) in the roll axis direction, is detected. The width direction belt position shift amount calculating means (C2) is provided with the width direction belt position sensor (SN).
The widthwise belt position shift amount Bs (=) between the widthwise belt detection position B0 and the widthwise belt reference position Ba detected in b).
Ba−B0) is calculated.

The rotation position of the stepping motor (M2) for holding the belt (B) at the widthwise belt reference position Ba is θa, and the rotation position of the stepping motor when the widthwise belt detection position B0 is detected is θ0. The amount of rotation of the motor (M2) in one step is Δθ (Δθ is positive or negative), and the motor rotation position determined each time the stepping motor rotation position θ0 rotates one step in a fixed direction is θi (i = 0, 1, 2, ,...), The motor rotation position determination means (C4) for controlling the position holding time ratio controls the motor rotation adjustment amount θs determined according to the Bs (= Ba−B0).
When (= θa−θ0) is θi ≦ θs <θi + 1 (that is, when iΔθ ≦ θs <(i + 1) Δθ), the motor rotation positions θi and θi + 1 are determined. The position holding time ratio calculating means (C5) is a position holding time ratio which is a ratio of a time for holding the motor rotation position at θi to a time for holding the motor rotation position at θi + 1, and corresponds to the motor rotation position θa. The position holding time ratio for holding the belt (B) at the widthwise belt reference position Ba is calculated.

The motor rotation position adjustment signal output means (C
6) is the rotational position θi of the stepping motor (M2).
Is output at the motor rotation position θi or θi + 1 at a time ratio corresponding to the position holding time ratio. In order to adjust the widthwise belt position, a belt position adjusting device (B
c) adjusting the roll axis tilt angle of the alignment adjustment roll (27) by adjusting the rotation position of the stepping motor (M2) according to the output signal of the motor rotation position adjustment signal output means (C6). By adjusting the roll shaft inclination angle as described above, the belt (B) can always be held at the reference position in the width direction belt, so that the belt (B) can be used without using any special parts. The meandering amount can be reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Embodiment 1 of the present invention is characterized in that the present invention has the following requirement (A010). (A010) The width direction displacement amount Bs (= Ba−B)
0), the motor rotation position adjustment signal output means (M) outputs a motor rotation position adjustment signal for adjusting the displacement of the stepping motor (M2) as the number of steps n (n is an integer) of the stepping motor (M2). C6). (Operation of the First Embodiment) In the first embodiment of the present invention having the above-described configuration, the motor rotation position adjustment signal output means (C6) outputs the stepping motor (M2 ) Is output as the step number n (n is an integer) of the stepping motor (M2). Therefore, the belt position adjusting device (Bc) rotates the stepping motor (M2) by the number of steps n output from the motor rotational position adjusting signal output means (C6), thereby rotating the alignment adjusting roll (27). Adjust the tilt angle.

[0015]

Next, with reference to the drawings, an embodiment (that is, an embodiment) of a belt device according to the present invention will be described. However, the present invention is not limited to the following embodiment. (Embodiment 1) FIG. 1 is an explanatory view of an image forming apparatus provided with a belt device according to Embodiment 1 of the present invention. In FIG. 1, an image forming apparatus F capable of color copying includes a UI (user interface) having a copy start key, a numeric keypad, a display unit, and the like on an upper part, and a transparent platen glass 2 on which a document (not shown) is placed. And An exposure optical system 5 having a document illumination unit 3 and a mirror unit 4 for scanning while illuminating the document on the platen glass 2 is arranged below the platen glass 2. The original image light reflected by the original on the platen glass 2 exposed by the exposure optical system 5 passes through the exposure optical system 5 and the imaging lens 6,
The image is read as R, G, B analog signals by a CCD (color image reading sensor).

The R (red), G (green), and B (blue) image signals read by the CCD are input to an IPS (image processing system). The IPS includes an image read data output unit 11 that converts an analog electric signal of the read image of R, G, and B into a digital signal and outputs the digital signal, and K (black), Y (yellow), and M ( An image data output unit 12 that converts the image data into magenta) and C (cyan) image data, performs data processing such as density correction and enlargement / reduction correction, and outputs the image data as writing image data (laser driving data). I have. The image data output means 12 has an image memory 13 for temporarily storing the K, Y, M, C image data.

The laser drive signal output device 14 is provided with the IP
The laser drive signal of the image of each color K, Y, M, C component according to the image data input from the S write image data output means 12 is transmitted at a predetermined timing to the ROS (optical scanning device,
That is, the image data is output to the latent image forming apparatus. The ROS is
An electrostatic latent image writing position Q1 on the image carrier 16 is controlled by the laser beam L modulated by the input laser drive signal.
Is scanned. A charger 17 for uniformly charging the image carrier 16 is disposed along the rotating image carrier 16 and upstream of the latent image writing position Q1 in the moving direction of the image carrier 16. After the image carrier 16 is uniformly charged by the charger 17, an electrostatic latent image is written by the laser beam L at the latent image writing position Q1.

A rotary developing device G for developing the electrostatic latent image into a toner image is provided in a developing area Q2 downstream of the latent image writing position Q1 along the moving direction of the image carrier 16. Are located. The developing device G includes K (black), Y (yellow), M (magenta), and
It has four color developing units Gk, Gy, Gm, Gc for developing toner images of each color of C (cyan), and the four color developing units Gk, Gy, Gm and Gc sequentially move to the development area Q2.

Below the rotating image carrier 16, an intermediate transfer belt (intermediate transfer member) B to which the toner image formed on the image carrier 16 is transferred is disposed. The intermediate transfer belt B passes through a primary transfer area Q3 set downstream of the developing area Q2 along a surface of the rotating image carrier 16 and a secondary transfer area Q4 below the primary transfer area Q3. Are located. A primary transfer corotron (primary transfer unit) 21 is disposed in the primary transfer area Q3.

In FIG. 1, the rotating image carrier 16
The image carrier cleaner 22 and the static elimination lamp 23 are disposed downstream of the primary transfer area Q3. In addition, it is possible to use a static elimination roll instead of the static elimination lamp 23. The intermediate transfer belt B includes a drive roll 25, an idler roll 26, an alignment adjustment roll 27 also serving as a tension roll (a roll for adjusting the position of the intermediate transfer belt B in the width direction, which will be described in detail later), an idler roll 28, and an inner roll 2. The image carrier 1 is stretched by belt support rolls (25 to 29) such as a next transfer roll (backup roll) 29, and is driven by a driving device (not shown).
6 at a speed substantially equal to that of the driving roller 25 in the direction of the arrow A via the driving roll 25. As shown in FIG. 4, the drive roll 25 is driven to rotate by an intermediate transfer belt drive motor M1, and the intermediate transfer belt drive motor M1 is driven by an output signal of a controller C.
Rotated by 1

FIG. 2 is an explanatory diagram of the intermediate transfer belt and the width direction belt position sensor whose width direction belt position is adjusted by the alignment adjusting roll. 3 is an explanatory view of an alignment adjusting roll, FIG. 3A is an explanatory view of an alignment adjusting roll and members supporting the alignment adjusting roll, and FIG. 3B is an enlarged cross-sectional view taken along the line IIIB-IIIB of FIG. 3A. FIG. 4 is a block diagram of a control unit of the image forming apparatus provided with the belt device according to the first embodiment of the present invention. Figure 1,
4, the widthwise position of the intermediate transfer belt B is detected by a widthwise belt position sensor SNb (see FIG. 2). The widthwise belt position sensor SNb is a sensor that detects the position of the side edge of the intermediate transfer belt B, and various conventionally known sensors can be used. A width direction belt position detection signal detected by the width direction belt position sensor SNb is input to a controller (see FIGS. 1 and 4).

In the secondary transfer area Q4, an outer secondary transfer roll 30 is disposed on a side facing the inner secondary transfer roll 29 with the intermediate transfer belt B interposed therebetween.
The inner secondary transfer roll 29 and the outer secondary transfer roll 30 constitute a secondary transfer unit 31 of this embodiment. The electrode roll 31 is connected to a transfer power supply circuit 32 (FIG. 1).
), And the core material of the outer secondary transfer roll 30 is grounded. The transfer power supply circuit 32 is controlled by the controller C. This transfer power supply circuit 32
Applies a bias voltage having the same polarity as that of the toner to the inner transfer roller 29 when the transfer material S passes through the secondary transfer area Q4, and transfers the toner image on the intermediate transfer belt B to the transfer material S.
Transfer to

The outer secondary transfer roll 30 is connected to the inner
In a state where the transfer roller 29 is moved away from the next transfer roll 29 and the intermediate transfer belt B, the transfer roll is cleaned by the transfer roll cleaner 33, and foreign matters such as toner particles and paper dust attached to the surface are removed. Further, in the transport direction of the intermediate transfer belt B, on the downstream side of the outer secondary transfer roll 30, a peeling claw 3 for peeling the transfer material S from the surface of the intermediate transfer belt B
4 and an intermediate transfer member cleaner 35 for removing residual toner on the surface of the intermediate transfer belt B. The outer secondary transfer roll 30, the peeling claw 34, and the intermediate transfer member cleaner 35 are pressed against the intermediate transfer belt B,
It is configured to be separable.

From the paper feed tray 36 to the pickup roll 3
The transfer material S taken out by the transfer roller 38
The sheet is conveyed by a separating roll 38 composed of a and a retard roll 38b, temporarily stopped by a registration roll 39, and conveyed to the secondary transfer area Q4 through a guide conveying path 41 at a predetermined timing. The intermediate transfer belt B is applied to the transfer material S when passing through the secondary transfer area Q4.
The upper unfixed toner image is secondarily transferred. The transfer material S to which the unfixed toner image has been transferred moves along the upper surface of the sheet guide member 42, and is further conveyed to the fixing position Q5 through the conveyance belt 43. When the transfer material S passes through the fixing position Q5, the unfixed toner image on the transfer material S
4 and is discharged to the discharge tray 46.

In FIGS. 1 and 3, bearings 51 are mounted on both ends of the roll shaft 27a of the alignment adjusting roll 27. The bearings 51 are guide members (see FIG. 3) 52 at both ends of a roll support member 52 extending along the roll axis.
a and 52a are slidably supported.
The bearing 51 is constantly pressed outward (by the intermediate transfer belt B) by a compression spring 53. An inclined shaft 54 is fixed to the center of the roll support member 52 in the roll axis direction. The inclined shaft 54 is connected to the belt support roll 25.
To 29 are rotatably supported by a frame Fr (see FIG. 1) supporting the same.

In FIG. 3, the roll supporting member 52 is
Both sides of the inclined shaft 54 are connected to the frame Fr by tension springs 55, 55, and are held in a predetermined posture. Guide member 52 at one end of roll support member 52
The eccentric cam 56 is in contact with the lower surface of a.
By rotating the roller 6, the roll support member 52 and the roll shaft 27a of the alignment adjustment roll 27 supported by the roll support member 52 are inclined. The eccentric cam 56 includes a cam driving stepping motor M2 shown in FIG.
, And the cam driving stepping motor M2 is configured to be rotationally driven by an eccentric cam driving circuit D2 which is operated by an output signal of the controller C. By the rotation of the eccentric cam 56, the roll shaft 27a of the alignment adjusting roll 27 is tilted, so that the roll shaft tilt angle is adjusted. The code D
The elements indicated by 2, M2, 56, etc. constitute a belt position adjusting device Bc.

(Description of Control Unit of First Embodiment) FIG. 4 is a block diagram of a control unit of an image forming apparatus provided with a belt device according to a first embodiment of the present invention. Interface) is connected,
The UI includes a copy start key UIa, a copy number input key UIb, a display UIc, and the like. The controller C to which the input signal from the UI, the detection signal of the width direction belt position sensor SNb, and the like is input outputs operation signals of the intermediate transfer belt motor drive circuit D1, the eccentric cam drive circuit D2, and the like. .

The controller C, which executes a process corresponding to each of the input signals and outputs a control signal, performs I / O for inputting / outputting signals to / from external devices and adjusting input / output signal levels.
(Input / output interface), ROM (read only memory) storing programs and data for performing necessary processing, RAM (random access memory) for temporarily storing necessary data, and the ROM And a computer having a CPU (Central Processing Unit) for performing input / output control and arithmetic processing in accordance with the program stored in the ROM. Various functions are realized by executing the program stored in the ROM. can do. That is, the controller C has the following functions.

C1: Belt drive signal output means The belt drive signal output means C1 outputs a belt drive signal for rotating and stopping the intermediate transfer belt B. CM1: Belt reference position storage means The belt reference position storage means CM1 is a reference position of the width direction belt position (a set target position in the width direction of the belt) Ba.
Is stored. C2: Width direction belt position shift amount calculation means The width direction belt position shift amount calculation means C2 is a width direction belt position between the width direction belt detection position B0 detected by the width direction belt position sensor SNb and the width direction belt reference position Ba. The shift amount Bs (= Ba−B0) is calculated. C3: Motor rotation adjustment amount calculation means The motor rotation adjustment amount calculation means C3 has a Bs-θs correspondence table storage table C3m, and the width direction belt position shift amount Bs
(= Ba−B0) motor rotation adjustment amount θs (= θa
−θ0) is calculated. The motor rotation adjustment amount calculating means C3 can be configured as follows. That is, there is a fixed relationship between the belt width direction belt position deviation amount Bs and the motor rotation adjustment amount θs. Then, the belt position deviation amount Bs in the belt width direction is detected 50 times while the belt is pointed once, and the latest detected value is Bs0, the previous detected value is Bs1, and the previous and previous detected values are Bs2. In this case, the motor rotation adjustment amount θs is determined by the following equation. θs = K {Bs0 + K1Bs1 + K2Bs2} where K, K1, and K2 are constants determined by experimental results.
Therefore, the motor rotation adjustment amount calculating means C3 can be configured to calculate the motor rotation adjustment amount θs by the above equation.

C4: Motor rotation position determining means for position holding time ratio control Motor rotation position determining means for position holding time ratio control
Is the rotation position of a stepping motor (cam drive stepping motor) M2 for holding the belt at the widthwise belt reference position Ba, θa, and the rotation position of the stepping motor when the widthwise belt detection position B0 is detected is θ0, The motor rotation position determined for each rotation of the one step is θi
(I = 0, 1, 2,...), 1 of the stepping motor M2
When the rotation amount of the step is Δθ = (θi + 1−θi) and the motor rotation adjustment amount is θs = θa−θ0, θi <θs <θi + 1
Θi and θi + 1 that satisfy the conditions are determined. The above θs = (θa
If the value of -θ0) is negative, it means that it rotates to the opposite side (reverse rotation) to the rotation when the value of θs is positive (forward rotation).

C5: Position holding time ratio calculating means The position holding time ratio calculating means C5 includes a time Ti for holding the motor rotation position at θi and a time Ti for holding the motor rotation position at θi + 1.
A position holding time ratio (Ti: Ti + 1) which is a ratio with respect to +1 and calculates a position holding time ratio for holding the belt at the widthwise belt reference position Ba corresponding to the motor rotation position θa. I do. C6: motor rotation position adjustment signal output means, motor rotation position adjustment signal output means C6 adjusts the motor rotation position of a stepping motor (cam drive stepping motor) M2 that adjusts the roll axis inclination angle according to the width direction displacement amount. Output a signal. The motor rotation position adjustment signal output means C6 holds the rotation position of the stepping motor M2 at the motor rotation position θi or θi + 1 at a time ratio corresponding to the position holding time ratio (Ti: Ti + 1). A motor rotation position adjustment signal for controlling the position holding time ratio is output.

(Operation of the Embodiment) FIG. 5 is an explanatory diagram of the widthwise belt position control flow according to the embodiment of the present invention. The flow in FIG. 5 starts at the same time as the power of the image forming apparatus is turned on, and is executed in multitask in parallel with other control flows. In ST1 (step 1), it is determined whether or not the belt is rotating. If no (N), ST1 is repeatedly executed, and if yes (Y), the process moves to ST2. In ST2, the width direction belt position B0 is detected by the width direction belt position sensor SNb (see FIGS. 2 and 4). Next, ST3
In step (1), a difference (width direction belt position shift amount) Bs = (Ba−B0) between the width direction belt detection position B0 and the width direction belt reference position (belt target position) Ba is calculated.

Next, in ST4, when the rotation position of the stepping motor for holding the belt at the widthwise belt reference position Ba is θa, and the rotation position of the stepping motor when the widthwise belt detection position B0 is detected is θ0, The motor rotation adjustment amount θs (= θa−θ0) corresponding to the width direction belt position deviation amount Bs = (Ba−B0) is calculated. The motor rotation adjustment amount θs (= θa−θ0) is a value determined corresponding to the width direction belt position deviation amount Bs = (Ba−B0), and the Bs−θs correspondence table storage table C3m (FIG. 4).
).

In step ST5, the position holding time ratio control motor rotation position determining means sets the rotation amount of one step of the stepping motor (cam drive stepping motor) M2 to Δθ, and the rotation amount of the stepping motor M2 in a certain direction from the rotation position θ0. When the motor rotation position determined each time the motor rotates one step is θi (i = 0, 1, 2,...), The motor rotation adjustment amount θs (= θa−) determined according to Bs (= Ba−B0) (θ0) is θi ≦ θs <θi + 1 (that is, iΔθ ≦ θs <(i + 1) Δθ), the motor rotation positions θi and θi + 1 are determined.

Next, in ST6, in order to hold the belt at the belt reference position Ba, the motor rotation positions θi, θi + 1
Position holding time ratio (Ti: Ti + 1), which is the ratio of the time Ti, Ti + 1 for holding the stepping motor M2 for driving the cam.
Is calculated. The position holding time ratio (Ti: Ti + 1) can be easily calculated by the following equation (1). Ti: Ti + 1 = | θi + 1−θs |: | θs−θi | (1) Next, in ST7, the motor rotation signal output of the controller C shown in FIG. By means C6, a motor rotation position adjustment signal for rotating the cam driving stepping motor M2 to the motor rotation position θi is output. Next, ST8
It is determined whether the rotational position of the cam driving stepping motor M2 is at the motor rotational position θi.
If no (N), the process returns to ST1, and if yes (Y), the process moves to ST9. In ST9, a motor rotation position adjustment signal of the cam driving stepping motor M2 according to the position holding time ratio is output.

FIG. 6 is an explanatory diagram of the rotational position of the stepping motor M2 for driving the cam of the belt device according to the embodiment of the present invention, FIG. 6A is an explanatory diagram of the resolution of the stepping motor M2, and FIG. 6B is ST9 of FIG. FIG. 6C is a diagram showing the rotational position of the stepping motor M2, and FIG. 6C is a diagram showing the rotational position of the stepping motor M2. FIG. 7 is a diagram showing a case where the motor rotation position control is performed in a case where the same operation is performed. In FIG. 6A, the rotation amount of one step of the stepping motor M2 for driving the cam is Δ
θ (= θi + 1−θi), and the motor rotation stop position is (..., θi−1, θi, θi + 1,...).

In the first embodiment, the motor M2 for driving the cam is rotated at the motor rotation positions θi, θi in accordance with the position holding time ratio.
In the case of holding at i + 1, the control cycle is fixed, and the ratio of the time to hold at the motor rotational positions θi, θi + 1 is changed. 6B and 6C, the stepping motor M2
Rotates + Δθ when the rotation drive pulse (see FIG. 6B) is positive, and rotates −Δθ when the rotation drive pulse is negative. 6B and 6C, the motor rotation reference position θ
a is an intermediate value between θi and θi + 1 (θa = (θi + θi + 1) / 2 = θ
i + Δθ / 2). In this case, as shown in FIG. 6B, assuming that the ratio of the time Ti for holding the motor rotation position at θi to the value of Ti + 1 for holding θi + 1 is 1/1, the cam driving stepping motor M2 at that time is The rotational position θs is substantially the same as the case where the rotational position is moved to the position of θi + Δθ / 2 = θa.

FIG. 7 is an explanatory diagram when the motor rotation reference position θa is located at an arbitrary position between θi and θi + 1.
7A is an explanatory diagram of a motor rotational position adjustment signal output in ST9 of FIG. 5, FIG. 7B is a diagram showing the rotational position of the stepping motor M2, and FIGS. 7A and 7B are FIGS. 6B and 6C, respectively. FIG. In the example shown in FIG. 7, as in the case of FIG. 6, the control cycle is fixed, and the ratio of the time to be held at the motor rotational positions θi, θi + 1 is changed. In FIG. 7, the motor rotation position is θi
The rotation position θs of the cam driving stepping motor M2 can be set to an arbitrary position between the above-mentioned θi and θi + 1 by arbitrarily setting the ratio between the time Ti to be held at θi and the value of Ti + 1 to be held at θi + 1. Can be substantially maintained.

As described above, the resolution of the stepping motor M2 for driving the cam is already determined (FIG. 6A).
In this case, the resolution of the stepping motor M2 can be substantially increased by controlling the time ratio (position holding time ratio) during which the stepping motor M2 is held at the rotational position θi, θi + 1 in each step. By changing the time ratio (position holding time ratio),
The inclination angle of the roll shaft 27a of the alignment adjustment roll 27 can be held at an arbitrary position.

(Embodiment 2) FIG. 8 shows a motor for substantially holding the motor rotational position of the embodiment 2 at an arbitrary position between the rotational positions θi and θi + 1 in each step of the stepping motor M2. FIG. 8A is a diagram illustrating a rotation position adjustment signal and a motor rotation position, FIG. 8A is a diagram illustrating a motor rotation position adjustment signal, and FIG. The second embodiment of the belt device of the present invention shown in FIG. 8 is different from the first embodiment in the motor rotation position adjustment signal of the stepping motor M2 for driving the cam, but is otherwise the same as the first embodiment. In FIG. 8, the shorter one of the time for holding the motor rotation position at θi and the time for holding it at θi + 1 (for example, the time at θi + 1) is fixed, and the other is variable. And In the second embodiment, similarly to the first embodiment, the roll shaft 27 of the alignment adjusting roll 27 is used.
The inclination angle of a can be held at an arbitrary position.

(Embodiment 3) FIG. 9 shows a motor for substantially holding the motor rotational position of the embodiment 3 at an arbitrary position between the rotational positions θi and θi + 1 in each step of the stepping motor M2. FIG. 9A is a diagram illustrating the rotational position, and FIG. 9B is a diagram illustrating the motor rotational position when the control cycle is constant, and is a diagram corresponding to a case where one of the motor rotational positions has a position holding time ratio of 20 to 80%. FIG. 4 is a diagram showing a motor rotation position when a control cycle is made variable, and is a diagram corresponding to a case where one position holding time ratio of the motor rotation position is 0 to 20%. In the second embodiment of the belt device of the present invention shown in FIG. 9, the motor rotation position adjustment signal of the stepping motor M2 for driving the cam is used in combination with any one of the first and second embodiments. The other points are the same as in the first and second embodiments. In the third embodiment, as in the first embodiment, the inclination angle of the roll shaft 27a of the alignment adjustment roll 27 can be maintained at an arbitrary position.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention can be applied to belts other than the intermediate transfer belt, for example, a sheet conveying belt and a belt for forming an electrostatic latent image.

[0043]

The belt device of the present invention has the following effects. (E01) The meandering amount of the belt can be reduced without using any special parts. In addition, since a stepping motor is used, the inclination angle of the roll axis of the alignment adjustment roll can be maintained even when the power is off, so that the meandering amount of the belt can be reduced with high accuracy immediately after the power is turned on again. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an image forming apparatus including a belt device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of an intermediate transfer belt whose width direction belt position is adjusted by an alignment adjustment roll and a width direction belt position sensor.

FIG. 3 is an explanatory view of an alignment adjusting roll,
FIG. 3A is an explanatory view of an alignment adjusting roll and a member supporting the alignment adjusting roll, and FIG. 3B is an enlarged cross-sectional view taken along the line IIIB-IIIB of FIG. 3A.

FIG. 4 is a block diagram of a control unit of the image forming apparatus provided with the belt device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a widthwise belt position control flow according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram of a rotational position of a stepping motor for driving a cam of the belt device according to the embodiment of the present invention. FIG. 6A is an explanatory diagram of a resolution of a stepping motor M2.
FIG. 6B is an explanatory diagram of the motor rotation position adjustment signal output in ST9 of FIG. 5; FIG. 6C is a diagram showing the rotation position of the stepping motor M2; FIG. 11 is a diagram illustrating a case where the motor rotation position control is performed when substantially the same operation as when holding is performed.

FIG. 7 is an explanatory diagram when the motor rotation reference position θa is at an arbitrary position between the aforementioned θi and θi + 1;
7A is an explanatory diagram of a motor rotational position adjustment signal output in ST9 of FIG. 5, FIG. 7B is a diagram showing the rotational position of the stepping motor M2, and FIGS. 7A and 7B are FIGS. 6B and 6C, respectively. FIG.

FIG. 8 is a motor rotational position adjustment signal for substantially holding the motor rotational position of the second embodiment at an arbitrary position between the rotational positions θi and θi + 1 in each step of the stepping motor M2. FIG. 8A is a diagram showing a motor rotation position adjustment signal, and FIG.
FIG. 4 is an explanatory diagram of a motor rotation position.

FIG. 9 is a view for explaining a motor rotation position for substantially holding the motor rotation position of the third embodiment at an arbitrary position between the rotation positions θi and θi + 1 in each step of the stepping motor M2. 9A is a diagram showing the motor rotation position when the control cycle is fixed, and is a diagram corresponding to a case where one of the motor rotation positions is 20 to 80% of the position holding time, and FIG. 9B is a diagram showing the control cycle. FIG. 7 is a diagram showing a motor rotation position when is made variable, and is a diagram corresponding to a case where one position holding time ratio of the motor rotation position is 0 to 20%.

[Explanation of symbols]

B: Belt, B0: Width belt detection position, Ba: Width belt reference position, Bc: Belt position adjusting device for adjusting roll shaft inclination angle, Bs: Width belt displacement amount, C2 ...
Width direction belt position shift amount calculating means, C4 ... Position holding time ratio control motor rotation position determining means, C5 ... Position holding time ratio calculation means, C6 ... Motor rotation position adjustment signal output means, M2 ... (for cam drive) stepping Motor, SNb ...
Width direction belt position sensor, θa ... Stepping motor M2
, .Theta.0... The stepping motor rotation position when the width direction belt detection position B0 is detected, .DELTA..theta.
... A motor rotation position determined each time a step rotates in a fixed direction from the stepping motor rotation position θ0, a motor rotation adjustment amount determined according to θs... Bs, 25 a belt drive roll, 27 an alignment adjustment roll, 27a. Roll shaft (of a roll), (25-29) ... belt support roll,

(72) Inventor Junichiro Samejima 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Satoshi Fukada 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. A belt device having the following requirements (A01) to (A09): (A01) a belt driving roll and an alignment adjusting roll capable of adjusting a tilt angle of a roll shaft from a reference posture. A belt rotatably supported by a plurality of belt supporting rolls including: (A02) a belt position adjusting device that adjusts a roll axis tilt angle of the alignment adjusting roll by adjusting a rotation position of a stepping motor in step units; A03) A width direction belt position sensor for detecting a width direction belt position which is a position of the belt in the roll axis direction of the belt support roll,
4) The widthwise belt position shift amount Bs (= Ba−B), which is the amount of shift between the widthwise belt detection position B0 detected by the widthwise belt position sensor and the widthwise belt reference position Ba.
(A0) for detecting the widthwise belt position deviation amount calculating means;
5) Motor rotation position adjustment signal output means for outputting a rotation position adjustment signal of the stepping motor for adjusting the roll axis inclination angle in accordance with the width direction position deviation amount, (A06) moving the belt to the width direction belt reference position Ba The rotation position of the stepping motor for holding is θa, and the rotation position of the stepping motor when the width direction belt detection position B0 is detected is θ0.
And the rotation amount of one step of the stepping motor is Δ
θ, the motor rotation position determined each time the motor rotates one step in the forward or reverse direction from the stepping motor rotation position θ0 is θi (i =..., -2, -1, 0, 1, 2,. When the motor rotation adjustment amount θs (= θa−θ0) determined according to the Bs (= Ba−B0) is θi ≦ θs <θi + 1 (that is, iΔθ ≦ θs <(i + 1) Δθ). (A) a position holding time ratio controlling motor rotation position determining means for determining the motor rotation positions θi and θi + 1
07) Time to keep the motor rotation position at θi and θi
A position holding time ratio which is a ratio to a time for holding at +1 and calculates a position holding time ratio for holding the belt at the widthwise belt reference position Ba corresponding to the motor rotation position θa. Time ratio calculating means, (A08) A motor rotation position for position holding time ratio control for alternately holding the rotation position of the stepping motor at the motor rotation position θi or θi + 1 at a time ratio corresponding to the position holding time ratio. Said motor rotation position adjustment signal output means for outputting an adjustment signal; and (A09) adjusting the rotation position of said stepping motor in accordance with an output signal of said motor rotation position adjustment signal output means for adjusting said widthwise belt position. The belt position adjusting device. 2. The belt device according to claim 1, further comprising the following requirement (A010): (A010) a motor rotation for adjusting a displacement of the stepping motor according to the displacement in the width direction. The motor rotation position adjustment signal output means for outputting a position adjustment signal as a step number n (n is an integer) of the stepping motor.