JP2005181090A - Movement detection device, belt conveyance equipment, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a movement detection device which reduces the detection error in detecting the relative position to be detected, belt conveyance equipment, and an image forming device using it. <P>SOLUTION: The movement detection device detects the movement of an almost belt-shaped object 200 to be detected. It is arranged oppositely at one surface of the object 200 to be detected. An optical sensor 101 which detects the relative position of the surface of the object 200 to be detected and a supporting material 300 which is arranged oppositely at the other surface of the object to be detected are faced each other in parallel to the moving direction of the object 200 to be detected. An optical sensor module 100 is provided with a fluid fence 103 so as to surround a predetermined region which faces the object 200 to be detected, and a fan 102 which supplies high pressured fluid to the space surrounded by the fluid fence 103. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a movement amount detection device that detects the relative position of a detection target by emitting light to the detection target and detecting the light reflected thereby, and a belt conveyance device and an image forming apparatus provided with the same. In particular, the present invention relates to a movement amount detection device with a small measurement error of a movement amount of a detection target, a belt conveyance device using the same, and an image forming apparatus.

  Conventionally, in an image forming apparatus provided with a rotating body for image formation such as a photosensitive belt or an intermediate transfer belt, the position of an image on a transfer material conveyed by a rotary moving unit (belt) or rotary moving unit is highly accurate. Therefore, it is necessary to accurately control the movement amount and position of the rotational movement unit.

  However, if the rotational angular velocity of the rotating body fluctuates for some reason, the moving amount and moving position of the rotary moving unit also fluctuate, which causes a deviation in the position of the image on the transfer material conveyed.

  As disclosed in Patent Document 1, an endless belt-like rotator such as a transfer belt or a paper transport belt is used to control an image position error due to a movement speed variation of a rotational movement unit of a rotator with high accuracy. A rotary motor is directly connected to a rotary shaft of a driving roller to be driven or a rotary shaft of a cylindrical member such as a photosensitive drum, and a drive motor which is a driving means for the rotary body based on the rotational angular velocity of the rotary body detected by the rotary encoder There is known an image forming apparatus that controls the rotational angular velocity of the image.

  The image forming apparatus indirectly controls the moving amount (moving position) of the rotating moving unit of the rotating body by controlling the rotational angular velocity of the rotating body.

  In contrast, the inventions disclosed in Patent Documents 2 to 4 calculate the speed of the surface of the rotational movement unit from the pulse interval obtained by forming a mark on the surface of the rotational movement unit and detecting the mark with a sensor. Thus, the drive means of the rotating body is feedback controlled. According to this method, since the behavior of the surface of the rotational movement unit can be directly observed, the movement amount of the rotational movement unit can be directly controlled.

  When a mark is formed on the surface of the rotationally moving portion, the mark is detected by the sensor, and the mark is detected by the sensor, as shown in FIG. 3A, the relative positional relationship between the sensor and the mark to be detected If there is no fluctuation, no detection error will occur, but if the relative positional relationship (detection distance or angle) between the sensor and the detection target (the mark formed on the surface of the rotational movement part) changes, the detection target It is recognized as moving, and an error is included in the detected movement amount. For example, as shown in FIG. 3B, when a mark is detected using an optical sensor, the mark portion (detected region) of the rotationally moving portion irradiated with light varies (moves) depending on the light irradiation direction. And it will be observed as an error.

  Also, in the method of directly connecting the rotary encoder to the rotating shaft, a casing-enclosed rotary encoder can be applied, and it can be installed in a place relatively far from the image forming part (a place where toner scattering is relatively small). Is small. However, in the case where a mark is formed on the surface of the rotary moving part and the mark is detected by a sensor, it is structurally difficult to completely casing the mark and the sensor. In the case of the image forming apparatus, a mark is formed on the surface of the rotational movement unit that is an image forming unit. This is a place where toner scattering is relatively large. For this reason, marks and sensors are easily contaminated by scattered toner, and errors are likely to occur.

  Here, the fact that the influence of dirt becomes large means that the mark formed on the rotational movement part is dirty and difficult to be recognized by the sensor. As shown in FIG. 4A, when an optical sensor is used, the light emitted from the LED is reflected by the surface of the detection target (mark), and the reflected light enters the light receiving element to detect the mark. The However, when dirt adheres to the mark, the light transmittance or reflectance at that part changes, or as shown in FIG. 4B, dirt adheres to the light emitting part or light receiving part of the sensor. As a result, the amount of light detected by the light receiving unit decreases. In such a state, the light entering the light receiving element is reduced, and the output from the sensor (analog output) is reduced. Further, when the light amount detected by the light receiving unit of the sensor is reduced to zero, a binarized signal that should be output by converting the sensor output is not output.

  As described above, in the conventional movement amount detection device, if the relative positional relationship between the sensor and the detection target changes or if dirt is attached to the detection target or the surface of the sensor, an error is included in the detection result. There was a problem.

  As a conventional technique for solving such a problem, there is a “relative position detecting device” disclosed in Patent Document 5 and a “foreign substance removing device for image forming apparatus” disclosed in Patent Document 6.

  In the relative position detection device that detects the amount of movement of a moving body using light, the invention disclosed in Patent Document 5 is based on contact damage or dust adhesion by increasing the distance between the scale and the index scale. The invention aims to improve the degree of freedom with respect to the movement of the scale in the direction perpendicular to the moving direction of the scale and the inclination of the scale.

The invention disclosed in Patent Document 6 is to periodically blow off dust adhering to the sensor with air.
Japanese Patent No. 3107259 JP-A-6-263281 JP-A-9-114348 JP 11-24507 A JP-A-11-166809 JP 2000-280452 A

The invention disclosed in Patent Document 1 is to reduce errors caused by displacement of the detection position when the scale is damaged due to contact or the detection distance (distance between the light projecting / receiving section and the scale) changes during measurement. belongs to.
However, this is an effective method only when there is a ray in a plane perpendicular to the direction of scale movement, otherwise an error occurs due to movement in the direction of movement perpendicular to the direction of scale movement. End up. This is due to the influence of an attachment angle error of the sensor itself.

  Moreover, since the invention disclosed in Patent Document 2 does not reduce the relative position variation between the sensor and the detection target, a detection error occurs due to this.

  As described above, conventionally, there has not been provided a movement amount detection device that takes into consideration both fluctuations in the relative positional relationship between the sensor and the detection target and adhesion of dust to the sensor or the detection target surface.

  The present invention has been made in view of such a problem, and a movement amount detection device in which a relative positional relationship between a sensor and a detection target is changed, and a detection error due to dust adhering to the surface of the sensor or the detection target is reduced. It is an object of the present invention to provide a belt conveyance device and an image forming apparatus using the same.

  In order to achieve the above object, the present invention provides, as a first aspect, a movement amount detection device for detecting a movement amount of a substantially band-shaped detection target, which is disposed to face one surface of the detection target, The optical sensor for detecting the relative position of the detection target surface and the support member arranged to face the other surface of the detection target are opposed in parallel to the movement direction of the detection target, and the optical sensor and the support member Either one of the features includes a fence erected so as to surround a predetermined region of the surface facing the detection target, and a high-pressure fluid supply means for supplying a high-pressure fluid to a space surrounded by the fence. A quantity detection device is provided. Thereby, these distances can be kept constant without bringing the optical sensor into contact with the detection target. In the above configuration, it is preferable to remove the foreign matter adhering to the surface of the detection target with the high-pressure fluid supplied by the high-pressure fluid supply means. Moreover, it is preferable that an optical sensor is provided with a fence and a high pressure fluid supply means. In this way, the movement amount detection error can be reduced.

  In order to achieve the above object, the present invention provides, as a second aspect, a belt conveyance device including the movement amount detection device according to any one of the first aspect of the present invention, wherein the detection target is An endless belt that is stretched between a driving roller that rotates by obtaining a driving torque from a motor and at least one driven roller and has one or more marks on the surface, and the optical sensor detects the marks. The present invention provides a belt conveying device having speed / position detecting means for calculating a moving speed and a moving amount of a detection target based on the interval. In this way, when detecting the belt conveyance speed and the amount of movement, the effect of fluctuations in the relative positional relationship between the detection target and the optical sensor, or the effect of dust adhering to the optical sensor or the detection target. No longer receive In the above configuration, it is preferable to further include means for controlling the rotation amount of the motor based on the calculation result calculated by the speed / position detection means. In this way, the belt conveyance speed can be controlled without being affected by fluctuations in the relative positional relationship between the detection target and the optical sensor, or affected by dust adhering to the optical sensor or detection target. it can.

  In order to achieve the above object, the present invention provides, as a third aspect, an image forming apparatus including the belt conveyance device according to any one of the second aspect of the present invention, wherein the endless belt includes: An image forming apparatus characterized by being a photosensitive belt used in an electrophotographic process is provided. In this way, it is possible to form a high-quality image without being affected by the relative positional relationship between the detection target and the optical sensor, or without being affected by dust adhering to the optical sensor or the detection target. .

  In order to achieve the above object, the present invention provides, as a fourth aspect, an image forming apparatus including the belt conveyance device according to any one of the second aspect of the present invention, wherein the endless belt includes: The endless belt provides an image forming apparatus that is a transfer belt or an intermediate transfer belt used in an electrophotographic process. In this way, it is possible to form a high-quality image without being affected by the relative positional relationship between the detection target and the optical sensor, or without being affected by dust adhering to the optical sensor or the detection target. .

[Action]
The present invention reduces the detection error of the movement amount by preventing the position of the detection target from being shifted in the direction perpendicular to the movement direction (or suppressing the deviation amount to an allowable range), and the detection target and the optical sensor. Preventing the sensor from coming into contact can prevent the optical sensor from becoming dirty or damaged.
The detection error of the amount of movement increases over time by using the high-pressure fluid used to prevent the position of the detection target from deviating in the direction perpendicular to the movement direction to remove or prevent contamination of the detection target and the optical sensor. Can be prevented.

  According to the present invention, the relative position between the optical sensor and the detection target can be kept at a constant distance without scratching the detection target. Also, if the conveyor belt of the belt conveyor device or the transfer belt or intermediate transfer belt of the image forming apparatus is a detection target, dirt is less likely to adhere to the optical sensor or belt, reducing detection errors and increasing the detection accuracy of the movement amount. Enhanced.

  According to the present invention, a movement amount detection device that reduces fluctuations in the relative positional relationship between the sensor and the detection target, and detection errors due to adhesion of dust to the sensor or the detection target surface, a belt conveyance device using the same, and an image A forming apparatus can be provided.

  A preferred embodiment of the present invention will be described. FIG. 1 shows a configuration of a movement amount detection apparatus 100 that preferably implements the present invention. The movement amount detection apparatus 100 includes an optical sensor 101 (LED 101a and light receiving element 101b), a blower 102, a fluid fence 103, and a support member 300, and keeps the distance between the optical sensor 101 and the detection target 200 constant. The hovercraft principle is applied.

  The movement amount detection device 100 is for increasing the pressure of the fluid (here, air) between the surface of the optical sensor 100 on the support member 300 side (the surface on which the LED 101 a emits light) and the detection target 200. A blower 102 is provided as a device. The blower 102 sends air to the area surrounded by the fluid fence 103 provided on the surface where the LED 101a emits light, so that the air whose pressure is increased remains between the detection target 200 and the air. .

  A part of the air sent to the area surrounded by the fluid fence 103 is blown to the detection target 200 and flows out from the gap between the detection target 200 and the fluid fence 103 to the outside. In addition, the detection target to which the high-pressure fluid is sprayed is in a state of being in contact with the support member 300.

  According to the above structure, the movement amount detection device 100 can keep the distance between the optical sensor 101 and the detection target 200 constant without the surface of the LED 101a that emits light contacting the detection target 200. .

  Furthermore, dust attached to the detection target 200 is removed by spraying the high-pressure fluid onto the detection target 200. For this reason, the dust adhering to the detection target 200 does not hinder the transmission and reflection of light, and the detection error is reduced.

  In addition, since the high-pressure fluid outlet is provided on the light emitting side of the LED 101 of the optical sensor 100, the high-pressure fluid does not approach the surface of the optical sensor 101. The light transmission is not hindered, and the detection error is reduced.

  Further, if the moving amount measuring mechanism having the above configuration is applied to a belt conveying device and the moving amount of the belt is detected using the moving amount measuring mechanism, the moving speed and the moving amount of the belt can be controlled to predetermined values. In this case, for example, the rotation amount of the motor that is the drive source of the belt may be controlled based on the detection result of the belt movement amount. As long as the type of belt is an image forming apparatus, the belt can be applied to a transfer belt and an intermediate transfer belt in an electrophotographic process in addition to a conveyance belt for conveying an image carrier. The present invention can be applied to all image forming apparatuses such as copying machines, printers, and facsimiles.

  Here, the configuration has been described in which the fluid fence 103 is provided on the optical sensor 101 side and air is sent into the region surrounded by the fluid fence 103, but the fluid fence 103 may be provided on the support member 300 side as shown in FIG. . In this case, the pressure of the high-pressure fluid may be adjusted so that the optical sensor 101 is positioned vertically upward and the force exerted on the detection target 200 by the high-pressure fluid and the weight of the detection target 200 are balanced. If the detection target 200 is a belt shape, the pressure of the high-pressure fluid can be adjusted so that the force exerted on the detection target 200 by the high-pressure fluid is balanced with the tension of the detection target 200. In this case, the optical sensor It is possible to arrange 101 on the top and bottom.

In addition, the said embodiment is an example of suitable implementation of this invention, and this invention is not limited to this.
For example, in the above embodiment, an example in which air is used as the fluid has been described. However, any compressible fluid can be applied to the present invention.
As described above, the present invention can be variously modified.

It is a figure which shows the structure of the movement amount detection apparatus which implemented this invention suitably. It is a figure which shows another structure of the movement amount detection apparatus which implemented this invention suitably. It is a figure which shows the cause which an error produces in a detection result by the fluctuation | variation of the relative position of an optical sensor and a detection target. It is a figure which shows the cause which an error produces in a detection result, when dirt adheres to an optical sensor.

Explanation of symbols

100 photosensor module 101 photosensor 101a LED
101b Light receiving element 102 Blower 103 Fluid fence 200 Object to be detected 300 Support member

Claims (7)

A movement amount detection device for detecting a movement amount of a substantially band-shaped detection target,
The optical sensor that is disposed to face one surface of the detection target and detects the relative position of the surface of the detection target, and the support member that is disposed to face the other surface of the detection target are the detection target. Facing in parallel with the moving direction of
Either one of the optical sensor and the support member is a fence erected so as to surround a predetermined region of a surface facing the detection target, and a high-pressure fluid supply unit that supplies a high-pressure fluid to a space surrounded by the fence A movement amount detection device comprising:   2. The movement amount detection apparatus according to claim 1, wherein the foreign matter adhering to the surface of the detection target is removed by the high pressure fluid supplied by the high pressure fluid supply means.   The movement amount detection device according to claim 1, wherein the optical sensor includes the fence and the high-pressure fluid supply unit. A belt conveyance device comprising the movement amount detection device according to any one of claims 1 to 3,
The detection object is an endless belt that is stretched between a driving roller that rotates by obtaining a driving torque from a motor and at least one driven roller, and has one or more marks on the surface,
A belt conveying apparatus comprising speed / position detecting means for calculating a moving speed and a moving amount of the detection target based on an interval at which the optical sensor detects the mark.   5. The belt conveying apparatus according to claim 4, further comprising means for controlling the amount of rotation of the motor based on a calculation result calculated by the speed / position detecting means.   6. An image forming apparatus comprising the belt conveying device according to claim 4, wherein the endless belt is a photosensitive belt used in an electrophotographic process.   6. An image forming apparatus comprising the belt conveyance device according to claim 4, wherein the endless belt is a transfer belt or an intermediate transfer belt used in an electrophotographic process.

Images