JP2006240815A - Rotating position sensing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating position sensing device capable of making feedback control of the moving speed or moving position of a high accuracy conveying belt. <P>SOLUTION: The rotating position sensing device has an endless conveying belt traveling upon being wound on a roller to make driven rotation with a torque of a motor and a roller different from the first named roller able to rotate freely, where marks are provided on one surface of the conveying belt, and is to sense the belt position by sensing marks, wherein the parallel linear marks are provided in positions perpendicularly intersecting the belt transporting direction and are sensed by a plurality of sensors arranged obliquely at constant intervals relative to one linear mark, and the moving speed or moving position of the conveying belt is subjected to a feedback control by reference to the signals of the linear marks which the sensors have sensed one by one. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotational position detection device and an image forming apparatus, and more specifically, to a rotational position detection device that rotates an endless belt, detects a mark written on the belt, and feedback-controls the rotation of the endless belt. The present invention relates to an image forming apparatus using a rotational position detection device.

  Since the gap in printing and the overlap (banding) have a great influence on the image quality, a high-speed and high-precision positioning control is required for the misalignment of the printing apparatus.

  In the ink jet recording system, a technique has been proposed in which a sheet is conveyed between conveyance rollers, and a rotary encoder of the driving roller or a rotary encoder is attached to the driving rotation axis to feedback control the rotation speed of the driving roller (Patent Document). 1). According to this technology, the detection position of the rotary encoder provided on the rotation shaft of the drive roller is moved away from the rotation center of the transport roller, and the resolution of the rotation position detection is improved by increasing the number of detection slits. Control becomes possible.

However, due to the eccentricity of the drive roller and the rotary encoder, there are problems that the amount of paper transport differs depending on the rotation angle of the transport roller, and there is a problem that the printing device cannot be downsized because the detection device becomes large.
In addition, even if the rotation angle of the driving roller is constant, there is a problem that the transport amount deviates from a predetermined position due to slippage between the thickness transport roller of the print paper and the print paper.
Further, when the printing paper is transported only by the transporting roller, a phenomenon occurs in which the printing paper becomes wavy due to moisture contained in the ink adhering to the printing paper. Due to this undulation phenomenon, the printing position is shifted, and the printing paper comes into contact with the nozzle surface of the ink head, and the ink on the nozzle surface adheres to the printing paper, thereby degrading the image quality.

In order to solve the above-mentioned problems, Patent Document 2 and Patent Document 3 propose a method in which a conveyor belt is conveyed by a plurality of driving rollers and speed control is performed by a belt detection unit of the conveyor belt.
As a result, the printing paper is transported in close contact with the transport belt, so that there is no printing smear, and accurate position detection can be performed without any position detection error due to eccentricity of the drive roller or slippage of the drive roller and the transport belt.
However, the detection of the position of the conveyor belt detects the mark written on the conveyor belt, so that the detection mark interval is wide, and a narrow mark interval can be detected for highly accurate position detection with a resolution of several tens of microns or less. An expensive detection device is required.
JP 2003-260841 A JP 2002-123056 A JP-A-9-175687

  As described above, when feedback control is performed on the rotational movement of the conveyance belt wound around the drive roller, a rotary encoder is fixed to the drive roller of the conveyance belt, and when the conveyance belt is driven and controlled by the output of the rotary encoder, There is a problem that the feeding accuracy of the conveying belt is lowered due to the eccentricity or the slippage of the driving roller and the conveying belt, and the image quality is deteriorated.

  In addition, when a position detection mark is provided on the conveyor belt and the rotational movement of the conveyor belt is feedback-controlled using this mark, the printing apparatus can be reduced in size, but the resolution for detecting the conveyor belt position is lower than that of the rotary encoder. There is a problem in that accurate feed control of the conveyor belt cannot be performed, and image quality is deteriorated.

  The present invention has been made in consideration of the above-described circumstances, and is equipped with a rotational position detection device capable of feedback-controlling the movement speed or movement position of a highly accurate conveyor belt and the rotational position detection device. An object of the present invention is to provide an image forming apparatus.

  In order to solve the above-mentioned problems, the invention described in claim 1 is provided with a roller that is driven to rotate by the rotational force of a motor, and an endless conveyor belt that is wound around a roller that is freely rotatable and another roller. In a rotational position detecting device in which a mark is attached to one side of the conveyor belt and the belt position is detected by detecting the mark, a plurality of parallel marks are arranged at positions orthogonal to the conveyor direction of the conveyor belt. The plurality of linear marks are detected by a plurality of sensors that are attached as linear marks and are inclined at equal intervals with respect to one linear mark, and the signals of the linear marks sequentially detected by the plurality of sensors are used as a reference. The moving speed or moving position of the conveyor belt is feedback-controlled.

  According to the second aspect of the present invention, a roller that is driven to rotate by the rotational force of the motor, and an endless conveyance belt that is wound around a roller that is freely rotatable separately from the roller are mounted. In a rotational position detecting device, in which a mark is attached and a belt position is detected by detecting the mark, a plurality of sensors are arranged in a straight line so as to be orthogonal to the conveying direction of the conveying belt, and the marks are adjacent sensors. A plurality of linear marks arranged so as to be shifted stepwise with respect to each other are attached at equal intervals, and the moving speed or moving position of the conveyor belt is determined based on the signals of the linear marks sequentially detected by the plurality of sensors. It is characterized by feedback control.

According to a third aspect of the present invention, in the rotational position detection device according to the first or second aspect, the plurality of sensors are mounted integrally.
According to a fourth aspect of the present invention, in the rotational position detecting device according to the first or second aspect, at least two of the plurality of sensors simultaneously detect a straight mark on the conveyor belt.

According to a fifth aspect of the present invention, in the rotational position detection device according to the first, second or fourth aspect, when the detection times of the two sensors to be detected at the same time are different, the other sensors are detected according to the shifted time. The detection time is corrected.
According to a sixth aspect of the present invention, in the rotational position detection device according to the fifth aspect, a correction amount for the shifted time is calculated and stored in a storage device.

  The invention according to claim 7 is an image forming apparatus equipped with the rotational position detection device according to claim 1 or 2, wherein the feedback control of the conveyance belt electrostatically attracts printing paper to the conveyance belt, The speed or position of movement in the sub-scanning direction is controlled by detection signals output from the plurality of sensors.

  According to the present invention, it is possible to provide a rotational position detection device capable of feedback-controlling the movement speed or movement position of a highly accurate transport belt, and an image forming apparatus equipped with this rotational position detection device.

Further, since the plurality of sensors of the detection mechanism are integrally formed, it can be easily attached.
In addition, since detection between sensors is constant, detection accuracy is improved and control can be performed with high accuracy.

  In addition, since at least one of the plurality of sensors of the detection mechanism detects the moving position of the conveyor belt at the same time, it is easy to confirm whether the detection of the marks is detected continuously at equal intervals, The moving speed or moving position can be feedback controlled.

Also, when the time for detecting the position of the conveyor belt at the same time is deviated, the control timing is set while correcting the detection time detected by other sensors according to the deviated time. It is possible to provide a highly accurate rotational position detection device that can be used.
Further, since the correction amount for the detection time shift of the detection mechanism that simultaneously detects the position of the conveyor belt is stored in the storage device, the correction becomes easy, and high speed and high accuracy can be handled.

  In the image forming apparatus, since it is possible to feedback control the moving speed or moving position of the conveyance belt with high accuracy, it is possible to provide high-precision and high-precision positioning control with few printing gaps and overlapping (banding). .

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to a rotational position detection device and an image forming apparatus of the invention will be described with reference to the drawings. In the following description, the image forming apparatus will be described as an ink jet recording apparatus. However, the present invention can be applied to any apparatus in which a mark is arranged on the conveyance belt and a device for detecting the position by detecting the mark is mounted.

  FIG. 1 is a schematic perspective view of a mechanism portion of an image forming apparatus to which the present invention is applied. In FIG. 1, an image forming apparatus (inkjet recording apparatus) includes a carriage 2 that can move in a main scanning direction inside a recording apparatus main body 1, an ink cartridge 3 that supplies ink to the carriage 2, and a carriage 2 that can freely move in the main scanning direction. A pulley 7 that drives the carriage 2 in the main scanning direction by rotationally moving the main guide lot 4 and the secondary guide rod 5 fixed to both sides below the carriage 2 and the belt 6 fixed to the carriage 2 so as to be movable is rotationally driven. A carriage driving motor 8 for driving the recording paper, a driving roller 9 for transporting the recording paper to an ink discharging portion under the carriage 2, and a tension roller 10 provided on the paper discharging side of the driving roller 9 and the driving roller 9. Of the endless transport belt 11 and the drive roller 9 that rotate and move while the sheet is adsorbed by the rotation of Conveying drive motor 14 that rotationally drives pulley 12 fixed to the part via timing belt 13, cleaning of ink adhering to the ink discharge part under carriage 2, recovery device 15 that recovers ink discharge failure, and the like. Yes.

FIG. 2 is a detailed side view of the paper transport mechanism.
Below the drive roller 9, a charging roller 17 for adsorbing the sheet 19 to the transport belt 11 is in contact with the transport belt 11. On the other hand, on the upper side of the driving roller 9, a pressure roller 18 is freely rotated on the driving roller 9 while being pressed against the conveying belt 11. The sheet 19 conveyed by a sheet conveying mechanism (not shown) is attracted to the conveying belt 11 charged by the charging roller 17, and the sheet 19 is brought into close contact with the conveying belt 11 by the pressure roller 18 and conveyed to the ink discharge portion 2 a below the carriage 2. To do.

A platen 20 is fixed to the inside of the lower side of the carriage 2 of the conveying belt 11 that is stretched between the driving roller 9 and the tension roller 10. A hole 21 is provided on the platen 20 on the drive roller 9 side, and a reflection type detection device 22 for detecting a position detection mark 29 written on the conveyor belt 11 is mounted in the hole 21 of the platen 20.
A guide roller 23 is fixed on the sheet 19 entrance side above the detection device 22 via the conveyance belt 11 in a state of being pressed against the platen 20 so that the conveyance belt 11 and the sheet 19 do not flutter. .

As the driving roller 9 rotates, the sheet 19 conveyed while being in close contact with the conveying belt 11 and being printed by the ink discharge portion 2a under the carriage 2 is removed from the conveying belt 11 by a sheet guide 24 fixed to the upper right of the tension roller 10. The paper is separated and transported to the paper discharge roller 25, and is transported to the paper receiving tray 27 by the paper discharge roller 25 and a spur 26 pressed against the paper discharge roller 25.
Below the tension roller 10, a gradual brush 28 is fixed in contact with the conveyor belt 11 to remove foreign matter adhering to the conveyor belt 11. The conveyor belt 11 that has been gradually electrified by the slow brush 28 is recharged by the charging roller 17.

  FIG. 3 is a cross-sectional view of the position detection mark 29 and the detection device 22 written on the conveyor belt 11, and FIG. 4 shows the sensors 22 a 1, 22 b 1, 22 c 1, 22 d 1 and the position detection mark 29 integrated with the detection device 22. FIG.

  On the conveyor belt 11, position detection marks 29 (indicated by 29a1 to 29f1 in FIG. 4) are written at equal intervals around the circumference of the conveyor belt 11 in the direction perpendicular to the rotation direction of the conveyor belt 11. It is. A platen 20 and a detection device 22 are mounted on the platen 20 below the position detection mark 29, so that the position detection mark 29 can be detected from the hole 21 of the platen 20.

  A plurality of reflective sensors 22a1, 22b1, 22c1, and 22d1 are integrated and fixed in a straight line with the detection device 22, and the detection device 22 includes both end sensors 22a1 and 22d1 among the sensors 22a1, 22b1, 22c1, and 22d1. Is fixed so that the position detection marks 29a1 and 29b1 adjacent to the position detection mark 29 can be detected simultaneously.

  When the transport belt 11 rotates, the position detection mark 29 moves in the arrow direction A, and the sensors 22a1, 22b1, and 22c1 of the detection device 22 sequentially detect the position detection mark 29b1. The sensor 22d1 detects the position detection mark 29c1 at the same time that the sensor 22a1 detects the position detection mark 29b1.

FIG. 5 is an explanatory view of the positions of another detection device 22 and a position detection mark 29.
The reflective sensors 22 a 2, 22 b 2, 22 c 2, and 22 d 2 of the detection device 22 are fixed in a straight line perpendicular to the rotation direction of the transport belt 11. The position detection marks 29 are written on the transport belt 11 at equal intervals, but corresponding to the sensors 22a2, 22b2, 22c2, and 22d2, the position detection marks 29 are adjacent to the adjacent sensors 22a2, 22b2, 22c2, and 22d2. 1/3 of the 29 intervals are shifted stepwise.

  When the sensor 22a2 detects the position detection mark 29b2, the sensor 22d2 simultaneously detects the position detection mark 29d2. The sensors 22b2 and 22c2 detect the position detection mark 29b2 with a delay after the sensor 22a2 detects the position detection mark 29b2.

  FIG. 6 is an explanatory diagram of detection timing when the sensors 22a, 22b, 22c, and 22d are normally detected with respect to the position detection mark 29. The horizontal axis is the time axis, and the vertical axis is the sensors 22a, 22b, and 22c. , 22d position detection mark 29 detection ON or OFF is displayed.

With respect to the detection pulse of the sensor 22a, the sensor 22b is detected at a timing of La that is shifted by 1/6 hour of the detection pulse width L of the sensor 22a.
The sensor 22c is detected at a timing of Lb that is shifted by 2/6 of the detection pulse width L of the sensor 22a.
The sensor 22d is detected at the same time as the sensor 22a.

  The detection pulse rising width and falling width of the sensors 22a, 22b, and 22c are set to the same time, and the output signals t1, t2, t3, t4, and the like at the rising and falling times detected by the sensors 22a, 22b, and 22c, respectively. t5 and t6 are sent to a motor drive control unit (not shown). Thus, 6 pulses are output at one pulse interval (L) of the sensor 22a.

FIG. 7 is an explanatory diagram of correction when both end sensors 22a and 22d of the detection device 22 do not detect at the same time.
When the attachment position of the detection device 22 is shifted with respect to the position detection mark 29 written on the conveyor belt 11, the detection of the sensors 22a and 22d does not detect the position detection mark 29 at the same time.
When the detection of the sensors 22a and 22d is detected with a time difference of t, the S value is calculated and stored at S = t / 3. As shown in FIG. 7, when the rise time of the sensor 22d is earlier than the rise time of the sensor 22a, the output of the sensor 22b is transmitted with a delay of S time, and the sensor 22c transmits with a delay of (S × 2) time.

  Conversely, if the rise time of the sensor 22d is later than the rise time of the sensor 22a, the output of the sensor 22b is transmitted earlier by S time, and the sensor 22c is transmitted earlier by (S × 2) time. As described above, the detection deviation is investigated at the time of shipment or periodically, and the deviation value is stored and corrected, so that highly accurate detection can be performed.

  Here, the four sensors 22a, 22b, 22c, and 22d have been described for detecting the position detection mark 29, but it goes without saying that the resolution can be improved by increasing the number of sensors.

1 is a schematic perspective view of a mechanism unit of an image forming apparatus to which the present invention is applied. FIG. 5 is a detailed side view of a paper transport mechanism unit. It is sectional drawing of the position detection mark written in the conveyance belt, and a detection apparatus. It is position explanatory drawing of the sensor integrated with the detection apparatus and a position detection mark. It is position explanatory drawing of another detection apparatus and a position detection mark. FIG. 10 is an explanatory diagram of detection timing when a sensor normally detects a position detection mark. It is correction | amendment explanatory drawing when the both-ends sensor of a detection apparatus does not detect simultaneously.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording device main body, 2 ... Carriage, 2a ... Ink discharge part, 3 ... Ink cartridge, 4 ... Main guide lot, 5 ... Subordinate guide rod, 6 ... Belt, 7 ... Pulley, 8 ... Carriage drive motor, 9 ... Drive Roller, 10 ... Tension roller, 11 ... Conveyance belt, 12 ... Pulley, 13 ... Timing belt, 14 ... Conveyance drive motor, 15 ... Recovery device, 17 ... Charging roller, 18 ... Pressure roller, 19 ... Paper, 20 ... Platen , 21 ... hole, 22 ... detection device, 22a, 22a1, 22a2, 22b, 22b1, 22b2, 22c, 22c1, 22c2, 22d, 22d1, 22d2 ... sensor, 23 ... guide roller, 24 ... paper guide, 25 ... paper discharge Roller, 26 ... Spur, 27 ... Paper cradle, 28 ... Gradual brush, 29 ... Position detection mark, 29a1, 29a2, 2 b1, 29b2, 29c1, 29d1, 29d2, 29e1, 29e2, 29f1, 29f2 ... position detection mark, L ... one pulse interval of the sensor 22a, La ... 1/6 hour of the detection pulse width L of the sensor 22a, t1 ... the sensor 22a Output signal detected at the time of rising, t2... Output signal at the time of rising detected by the sensor 22b, t3... Output signal at the time of rising detected by the sensor 22c, t4. The output signal at the time of rising detected by 22d, t5 ... the output signal at the time of falling detected by the sensor 22b, t6 ... the output signal at the time of falling detected by the sensor 22c, t ... A: Movement direction of the position detection mark.

Claims (7)

  A roller that is driven to rotate by the rotational force of the motor and an endless conveyor belt that is wound around the roller and another freely rotating roller are mounted, and a mark is attached to one side of the conveyor belt to detect the mark. In the rotational position detecting device for detecting the belt position, the mark is attached as a plurality of parallel straight marks at a position orthogonal to the transport direction of the transport belt, and inclined at equal intervals with respect to one straight mark. The plurality of linear marks are detected by a plurality of arranged sensors, and the moving speed or moving position of the conveyor belt is feedback-controlled based on the signals of the linear marks sequentially detected by the plurality of sensors. Rotation position detection device.   A roller that is driven to rotate by the rotational force of the motor and an endless conveyor belt that is wound around the roller and another freely rotating roller are mounted, and a mark is attached to one side of the conveyor belt to detect the mark. Thus, in the rotational position detection device that detects the belt position, the plurality of sensors are arranged in a straight line so as to be orthogonal to the transport direction of the transport belt, and the marks are shifted stepwise with respect to adjacent sensors. A plurality of linear marks arranged at equal intervals, and a rotation speed characterized by feedback control of the moving speed or moving position of the conveyor belt based on the signals of the linear marks sequentially detected by the plurality of sensors. Position detection device.   The rotational position detection device according to claim 1 or 2, wherein the plurality of sensors are mounted integrally.   The rotational position detection device according to claim 1, wherein at least two of the plurality of sensors simultaneously detect a linear mark on the conveyor belt.   5. The rotational position detection device according to claim 1, wherein when the detection times of the two sensors to be detected at the same time are different, the detection times of the other sensors are corrected according to the shifted time. Rotation position detection device.   6. The rotational position detection apparatus according to claim 5, wherein a correction amount for the shifted time is calculated and stored in a storage device.   3. An image forming apparatus equipped with the rotational position detection device according to claim 1 or 2, wherein the feedback control of the conveyance belt is performed by electrostatically adsorbing printing paper to the conveyance belt and detecting signals output from the plurality of sensors. Thus, the image forming apparatus is characterized in that the speed or position of movement in the sub-scanning direction is controlled.