JP2007147351A - Flatness measuring device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flatness measuring device and a flatness measuring method capable of measuring each flatness in a plurality of directions of a measuring object member which is a measuring object with a simple constitution. <P>SOLUTION: A circular pattern is irradiated onto a measuring object belt 12, and a projection pattern projected onto the measuring object belt 12 is imaged, to thereby acquire image data of the projection pattern, and the flatness in an optional direction is determined, based on a strain amount in the radius direction of the projection pattern included in an image of the acquired image data to a circular reference pattern. Consequently, each flatness in a plurality of directions of the measuring object belt 12 can be determined easily with a simple constitution by one-time measurement. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flatness measuring apparatus and a flatness measuring method, and in particular, is mounted on an image forming apparatus using an electrophotographic method such as an electrophotographic copying machine, a printer, a facsimile, and a composite machine thereof, and various apparatuses. The present invention relates to a flatness measuring apparatus and a flatness measuring method that use a sheet-like belt such as an intermediate transfer belt or a conveyance belt as a measurement target.

  Various apparatuses such as an image forming apparatus using an electrophotographic system are equipped with various belts such as a conveyance belt used as a conveyance member and a transfer belt onto which a toner image formed on an image carrier is transferred. .

  Belts used in these devices may require high flatness, and various devices for evaluating the flatness of the belt surface are known (see, for example, Patent Document 1 and Patent Document 2).

  According to the technique of Patent Document 1, a light and dark stripe-like light and dark pattern is projected on the surface to be inspected, and the degree of variation in the width of the light and dark boundary region of the light and dark pattern obtained by imaging the surface to be inspected is determined. The degree of smoothness is evaluated. However, with the technique of Patent Document 3, although the degree of smoothness can be evaluated, it has been difficult to measure flatness as a numerical value. Further, since only the variation in the width direction of the light / dark pattern is evaluated, it is difficult to evaluate the degree of smoothness in a plurality of directions.

  Further, as a technique applicable to the determination of flatness, in Patent Document 2, a pellicle as a measurement object is irradiated with a light beam having a linear shape, and the light beam having a linear shape is reflected by the pellicle and is generated. By receiving light and determining whether or not the shape of the light beam caused by the received reflected light is distorted, it is determined whether or not the pellicle surface is flat. However, even in the technique of Patent Document 2, it is possible to determine whether or not the surface of the pellicle as a measurement object is a flat surface, but it has not yet been possible to measure the flatness. Further, since the light beam has a linear shape, it is difficult to evaluate the flatness in a plurality of directions.

  As a measuring device and a measuring method for measuring the flatness of a measurement target member, in the techniques of Patent Document 3 and Patent Document 4, a laser displacement meter is moved in the axial direction with respect to an intermediate transfer member stretched by a pair of shafts. The difference between the maximum value and the minimum value of the displacement amount on the surface of the intermediate transfer member is calculated as flatness.

  Here, various belts mounted on various apparatuses of an image forming apparatus using an electrophotographic method have good flatness on the entire belt surface, not only in the width direction or the circumferential direction of the belt surface. Desired. However, in the techniques of Patent Document 3 and Patent Document 4, since the flatness in the belt width direction is measured, it is difficult to measure the flatness in a plurality of directions at a time.

In the technique of Patent Document 5, a pair of a light source that enters a light beam substantially perpendicularly to a mirror as a measurement object and an optical sensor that receives a reflected beam reflected by the mirror and detects a positional deviation of the reflected beam spot A plurality of projecting / receiving units are arranged on a plane parallel to the mirror, and the flatness of the mirror is measured by detecting the positional deviation of the reflected beam spot in the optical sensor of each projecting / receiving unit. According to the technique of Patent Document 5, it is possible to calculate flatness in a plurality of directions on the mirror surface based on detection results by a plurality of projecting and receiving units.
JP-A-9-126744 JP 10-38814 A JP 2002-148899 A JP 2004-181731 A Japanese Patent Laid-Open No. 5-40027

  However, the technique of Patent Document 5 is difficult to apply when the measurement target member has a configuration other than a mirror surface, and measures the flatness in a predetermined direction on the entire measurement target member or the entire measurement target member. However, it is necessary to provide a plurality of light sources and optical sensors over the entire surface of the measurement target member, which causes a problem that the apparatus configuration is complicated.

  The present invention has been made in consideration of the above facts, and provides a flatness measuring apparatus and a flatness measuring method capable of measuring the flatness in a plurality of directions of a measurement target member to be measured with a simple configuration. For the purpose.

  In order to achieve the above object, the flatness measuring apparatus of the present invention includes a projection unit that projects a circular pattern onto the surface of the measurement target member, and an image that indicates the projection pattern projected on the measurement target member by imaging. The amount of distortion in the radial direction of the projection pattern of the image data acquired by the imaging unit with respect to a predetermined reference pattern similar to the circular pattern and the imaging unit for acquiring data is set at a predetermined interval in the circumferential direction. Based on the absolute value of the difference between the maximum value and the minimum value of the strain amount in the directions opposite to each other, of the strain amount calculated by the strain amount calculating means Flatness calculation means for calculating the flatness in the direction of the measurement target member corresponding to the above.

The projection means of the flatness measuring apparatus of the present invention projects a circular pattern onto the surface of the measurement target member. Here, the “circular shape” indicates a shape indicated by a locus of points equidistant from a certain point (center).
When the flatness of the region of the measurement target member on which this pattern is projected is zero, a circular projection pattern is projected on the measurement target member, but when the flatness is not zero, A projection pattern having a distorted shape such as an elliptical shape instead of a circular shape is projected on the measurement target member. When the image data indicating the projection pattern projected on the measurement target member is acquired by imaging by the imaging unit, the distortion amount calculating unit is configured to capture the predetermined reference pattern similar to the perfect circle pattern. The amount of distortion in the radial direction of the projection pattern of the image data acquired by the above is calculated at predetermined intervals in the circumferential direction. The flatness calculating unit projects the distortion amount calculated by the distortion amount calculating unit based on the absolute value of the difference between the maximum value and the minimum value of the distortion amount in directions opposite to each other about the center of gravity of the projection pattern. The flatness of the direction of the member to be measured corresponding to the opposite directions of the pattern is calculated.

  As described above, the projection pattern of the image data obtained by projecting the circular pattern onto the surface of the measurement target member and imaging the projection pattern projected onto the measurement target member in the radial direction with respect to the circular reference pattern. The amount of distortion is calculated at predetermined intervals in the circumferential direction, and the absolute value of the difference between the maximum value and the minimum value of the amount of distortion in the opposite directions centered on the center of gravity of the projection pattern is calculated. Based on this, since the flatness of the direction on the measurement target member corresponding to the opposite direction is calculated, the flatness of the plurality of directions on the measurement target member can be easily calculated with a simple configuration.

  The flatness calculation means is for converting the absolute value of the difference between the maximum value and the minimum value of the distortion amounts in the directions opposite to each other into a value indicated by the international unit corresponding to the actual measurement value in the projection pattern on the measurement target member. Storage means for storing the conversion table in advance, and based on the conversion table stored in the storage means, the absolute value of the difference between the maximum value of the distortion amount in the opposite direction and the minimum value is indicated in international units. By converting to a value, the flatness in the corresponding direction on the measurement target member can be obtained.

  The flatness measuring apparatus of the present invention is configured to move a projection imaging unit including the projection unit and the imaging unit in the width direction of the measurement target member, and move the projection imaging unit at a predetermined interval. Control means for controlling the moving means to control the imaging means so that imaging is performed by the imaging means every time the moving means is moved at a predetermined interval, and the distortion amount calculating means comprises: Corresponding to the predetermined opposite direction of the member to be measured based on the absolute value of the difference between the maximum value and the minimum value among the distortion amounts in the predetermined opposite direction of the plurality of projection patterns acquired by The flatness of the direction can be calculated.

  Thus, by moving the projection imaging means in the width direction of the measurement target member, the flatness in a predetermined direction can be calculated from one end of the measurement target member in the width direction to the other end.

  The flatness measuring apparatus according to the present invention rotates a pair of stretching members that stretch the measurement target member and the measurement target member that is stretched by the pair of stretching members in a circumferential direction of the measurement target member. And a driving means for causing the movement to occur.

  By rotating the measurement target member in the circumferential direction by the driving unit, the projection unit can project a circular pattern in the circumferential direction of the measurement target member, and the imaging unit can also rotate the circumference of the measurement target member. Since the projection pattern can be imaged in the direction, the flatness in the predetermined direction can be calculated over the circumferential direction of the measurement target member.

  Further, by combining the projection imaging unit with a moving unit that moves the measurement target member in the width direction, the flatness in a predetermined direction can be calculated over the entire surface of the measurement target member.

  Note that the flatness in a plurality of directions of the measurement target member to be measured can be measured with a simple configuration by the following flatness measurement method. Specifically, a circular pattern is projected onto the surface of the measurement target member, and image data indicating the projection pattern projected on the measurement target member is acquired by imaging, and predetermined in advance to be similar to the circular pattern. The distortion amount in the radial direction of the projection pattern of the acquired image data with respect to the obtained reference pattern is calculated at a predetermined interval in the circumferential direction, and the maximum distortion amount in the opposite direction of the calculated distortion amount Based on the absolute value of the difference between the minimum value and the minimum value, the flatness of the measurement target member in the direction corresponding to the opposite direction is calculated.

  According to the flatness measuring apparatus and the belt flatness measuring method of the present invention, a circular pattern is projected onto the surface of the measurement target member, and image data obtained by imaging the projection pattern projected onto the measurement target member is captured. The amount of distortion in the radial direction of the projected pattern with respect to the circular reference pattern is calculated at predetermined intervals in the circumferential direction. Of the calculated amounts of distortion, the amounts of distortion in the opposite directions with respect to the center of gravity of the projected pattern Based on the absolute value of the difference between the maximum value and the minimum value, the flatness of the direction on the measurement target member corresponding to the opposite direction is calculated. It has the effect that it can be easily calculated with a simple configuration.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows the configuration of a flatness measuring apparatus 10 according to the present embodiment.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the flatness measuring device 10 of the present invention has a cylindrical roll 14 </ b> A, a cylindrical roll 14 </ b> B, and a cylindrical roll 14 </ b> A for extending a measurement target belt 12 to be measured for flatness in a predetermined direction. Drive unit 40 for rotationally driving, tension detecting sensor 47, stretching unit 42, output unit 38 for outputting various information to the outside of the apparatus, sensor 99, projection imaging unit 28, for acquiring various information from the outside of the apparatus An input unit 39 and a control unit 30 for controlling the apparatus main body are included.

  The drive unit 40, the tension detection sensor 47, the tension unit 42, the output unit 38, the sensor 99, the projection imaging unit 28, and the input unit 39 are connected to the control unit 30 so as to be able to exchange data and signals. Yes.

  The cylindrical roll 14A and the cylindrical roll 14B are arranged on the inner peripheral surface of the measurement target belt 12, and are arranged in parallel with each other at a predetermined interval so that the measurement target belt 12 can be bridged in the stretching direction. Has been.

  As shown in FIG. 2, both end portions in the axial direction of the cylindrical roll 14 </ b> A are rotatably supported by bearings 18 provided with an automatic alignment bearing 16, and the cylindrical roll 14 </ b> A is It is provided so that it can be centered around the center. The bearing 18 is supported by a housing (not shown) of the flatness measuring device 10.

  Each of the pair of bearings 18 is detachably fixed on a linear guide 26 mounted on the pair of rails 24. The pair of rails 24 extend so as to be parallel to each other so that the columnar roll 14A can move in a direction in which the columnar roll 14A and the columnar roll 14B are close to each other and in a direction in which they are separated from each other.

  For this reason, the cylindrical roll 14A supported by the pair of bearings 18 can move in a direction close to or away from the cylindrical roll 14B while being maintained parallel to the axial direction. Is provided.

  Both ends in the axial direction of the cylindrical roll 14B are also rotatably supported by bearings 20 (see FIG. 1). A pair of bearings 20 that support both ends in the axial direction of the cylindrical roll 14B are supported by a casing (not shown) of the flatness measuring device 10 via a support substrate 22, respectively.

  The bearing 20 may also be provided with a self-aligning bearing (not shown).

  At least one of the pair of bearings 18 that support the cylindrical roll 14 </ b> A is detachably provided from the cylindrical roll 14 </ b> A and the linear guide 26. Similarly, at least one of the pair of bearings 20 that support each of the cylindrical rolls 14B is detachably provided from the cylindrical roll 14B and a housing that is not shown.

  In this manner, at least one of the pair of bearings 18 that support the cylindrical roll 14A and at least one of the pair of bearings 20 that support the cylindrical roll 14B are detachable from the cylindrical roll 14A and the cylindrical roll 14B, respectively. By providing, it is comprised so that the measuring object belt 12 used as a measuring object can be spanned over the cylindrical roll 14A and the cylindrical roll 14B.

  In the vicinity of the cylindrical roll 14A, a detection sensor 99 is provided for detecting that the measurement target belt 12 is bridged between the cylindrical roll 14A and the cylindrical roll 14B.

  The tension detection sensor 47 detects the tension applied to the measurement target belt 12 spanned between the cylindrical roll 14 </ b> A and the cylindrical roll 14 </ b> B, and outputs the detection result to the control unit 30. As the tension detection sensor 47, for example, a pressure sensor for detecting tension may be included. This pressure sensor is provided on the outer peripheral surface of the cylindrical roll 14A at a position corresponding to the stretching direction end of the measurement target belt 12, and the axial direction of the cylindrical roll 14A from the measurement target belt 12 (by this pressure sensor) A signal corresponding to the pressure acting in the same direction as the stretching direction may be output to the control unit 30.

Further, in the flatness measuring apparatus 10 of the present invention, a circular pattern is formed on the surface of the measuring target belt 12 in order to measure the flatness of the measuring target belt 12 spanned between the cylindrical roll 14A and the cylindrical roll 14B. Is provided, and a projection imaging unit 28 including an imaging unit 50 that images a projection pattern 64 (see FIG. 4) projected onto the measurement target belt 12 by the projection unit 52.
Here, the “circular shape” indicates a shape indicated by a locus of points equidistant from a certain point (center).

  The projection imaging unit 28 includes a projection unit 52 that projects a circular pattern on the surface of the measurement target belt 12, an imaging unit 50 that images the projection pattern projected onto the measurement target belt 12 by the projection unit 52, and a half mirror 54. And.

  As shown in FIG. 3, the projection unit 52 includes a light source 52A such as a semiconductor laser that emits light. A collimating lens 52B for shaping the diffused light emitted from the light source 52A into substantially parallel light is provided on the light emitting side of the light source 52A. On the light exit side of the collimator lens 52B, in order to make the cross-sectional shape of the light beam emitted from the light source 52A circular, the surface aperture 52C provided with a circular hole 52D and the surface aperture 52C are passed. And a concave lens 55 for converting the emitted light beam into diffused light.

  The light emitted from the light source 52A passes through the surface aperture 52C provided with the circular hole 52D, so that the cross section becomes circular. Therefore, light having a circular cross section reaches the concave lens 55 and is converted into diffused light by the concave lens 55.

  A half mirror 54 is provided on the light exit side of the concave lens 55 so as to be inclined by 45 degrees with respect to a plane orthogonal to the optical axis of the light emitted from the concave lens 55. The half mirror 54 is a mirror having a characteristic of transmitting 50% and reflecting 50% of light.

  The diffused light emitted from the concave lens 55 is reflected by the half mirror 54 in the direction orthogonal to the optical axis W direction and toward the surface of the measurement target belt 12 stretched by the cylindrical roll 14A and the cylindrical roll 14B. Is done. Accordingly, when the flatness of the measurement target belt 12 is zero, that is, a flat surface, on the surface of the measurement target belt 12 stretched by the cylindrical roll 14A and the cylindrical roll 14B, a predetermined diameter Db is set. A circular projection pattern (hereinafter referred to as a reference pattern) 60 (see FIG. 5) is projected.

  As shown in FIG. 3, the imaging unit 50 includes a CCD (Charge Coupled Device) 72. The CCD 72 converts the reflected light indicating the area including the projection pattern 64 projected on the measurement target belt 12 obtained by the lens 70 (corresponding to the angle of view of the imaging unit 50) into analog image data indicating an image including the projection pattern 64. Convert to and output.

  The imaging unit 50 includes an analog processing unit 71, an analog / digital conversion unit (hereinafter referred to as A / D conversion unit) 73, a signal processing unit 77, a memory 76, a communication unit 78, and a CPU 74. .

  The CCD 72, the analog processing unit 71, the A / D conversion unit 73, the signal processing unit 77, the memory 76, the communication unit 78, and the CPU 74 can exchange signals with each other via a bus 79 such as a data bus or an address bus. It is connected.

The lens 70 and the CCD 72 are provided so that an area corresponding to the angle of view of the imaging unit 50 on the measurement target belt 12 including the projection pattern 64 projected on the measurement target belt 12 can be imaged. Specifically, when a reference belt with zero flatness is stretched between the cylindrical roll 14A and the cylindrical roll 14B, the position of the center of gravity of the circular reference pattern 60 projected onto the reference belt is: Even when the projection pattern 64 includes the projection pattern 64 projected onto the reference belt and extends in a predetermined direction, the projection pattern 64 is entirely overlapped with the optical axis of the lens 70 and the CCD 72. The angle of view of the imaging unit 50 is adjusted in advance so as to include a region.
As described above, the imaging unit 50 is configured so that image data of an image of an area including the projection pattern 64 projected on the measurement target belt 12 can be acquired by imaging of the imaging unit 50.

The analog processing unit 71 includes signal processing circuits such as a sampling hold circuit, a color separation circuit, and a gain adjustment circuit. The analog processing unit 71 performs a correlated double sampling process on the signal indicating the projection pattern 64 output from the CCD 72 and performs R, G, B Each color signal is subjected to color separation processing to adjust the signal level of each color signal. The A / D conversion unit 73 converts the analog signal processed by the analog processing unit 71 into a digital signal and outputs the digital signal to the signal processing unit 77.
An analog signal indicating an image including the projection pattern 64 output from the CCD 72 is processed by the analog processing unit 71, converted into a digital signal by the A / D conversion unit 73, and then converted into digital image data (hereinafter referred to as image data). Is input to the signal processing unit 77.

  The CPU 74 controls the overall operation of the imaging unit 50 and includes a microcomputer.

The signal processing unit 77 performs predetermined digital signal processing on the image data input from the A / D conversion unit 73 to obtain a gain adjustment circuit, a gamma correction circuit, and a luminance / color difference signal processing circuit (referred to as a YC processing circuit). It is comprised including. The image data input from the A / D converter 73 is amplified by the gain adjustment circuit, then subjected to gamma correction processing by the gamma correction circuit, and luminance (Y signal) and color difference signals (Cr, Predetermined digital signal processing to be converted into (Cb signal) is performed and stored in the memory 76. Therefore, the image data of the image including the projection pattern 64 projected on the measurement target belt 12 is stored in the memory 76 by the imaging process by the imaging unit 50.
The communication unit 78 is connected to the control unit 30 for controlling the entire flatness measuring apparatus 10 so as to be able to exchange signals. That is, the CPU 74 of the imaging unit 50 captures an area including the projection pattern 64 on the measurement target belt 12 based on an input signal input from the control unit 30 via the communication unit 78, and an image including the projection pattern 64. Are stored in the memory 76. Since the imaging unit 50 includes the communication unit 78, the control unit 30 is provided so as to be able to read image data of an image including the projection pattern 64 stored in the memory 76 of the imaging unit 50.

  As shown in FIG. 1, the projection imaging unit 28 is configured such that the cylindrical roll 14 </ b> B has an axis that can be moved from one end in the width direction of the measurement target belt 12 spanned between the cylindrical roll 14 </ b> A and the cylindrical roll 14 </ b> B. It is fixed to a linear guide 34 supported so as to be movable in the longitudinal direction of the rail 32 by a long rail 32 extending in the direction, that is, the direction parallel to the width direction of the belt 12 to be measured. The linear guide 34 is provided with a drive unit 36 for moving the linear guide 34 bidirectionally from one end side in the longitudinal direction of the rail 32 to the other end side.

  The drive unit 36 is connected to the control unit 30 so as to be able to send and receive signals, and moves the linear guide 34 from one end of the rail 32 to the other end under the control of the control unit 30. That is, the drive unit 36 is configured to be able to move the projection imaging unit 28 from one end to the other end in the width direction of the measurement target belt 12. In addition, the rail 32 is being fixed to the housing | casing which illustration of the flatness measuring apparatus 10 is abbreviate | omitted.

  The projection imaging unit 2 is controlled to move from one end to the other end of the rail 32 by being configured as described above and driving the drive unit 36 under the control of the control unit 30.

  The cylindrical roll 14B is provided with a drive unit 40 for rotating the cylindrical roll 14B in a predetermined direction via a gear (not shown).

  The drive unit 40 is connected to the control unit 30 so as to be able to exchange data and signals, and rotates the cylindrical roll 14B in a predetermined direction under the control of the control unit 30. The cylindrical roll 14A rotates following the rotation of the cylindrical roll 14B.

  For this reason, in the flatness measuring device 10, the measurement target belt 12 is stretched over the cylindrical roll 14B and the cylindrical roll 14A, and the cylindrical roll 14B is moved in a predetermined direction under the control of the control unit 30. Each time the linear guide 34 is driven and moved from one end side in the longitudinal direction of the rail 32 to the other end side (in the direction of the bidirectional arrow Y in FIG. 4), the cylindrical roll 14B and the cylindrical roll 14A. Is rotated and conveyed in the circumferential direction (in the direction of arrow X in FIG. 4), the projection imaging unit 28 projects a circular pattern over the entire outer peripheral surface of the measurement target belt 12. , And an image including the projection pattern 64 on the measurement target belt 12 can be captured.

  Moreover, the flatness measuring apparatus 10 of the present invention applies a predetermined load to the longitudinal direction of the measurement target belt 12 spanned between the columnar roll 14A and the columnar roll 14B and applies a predetermined load via the columnar roll 14A. A tension part 42 for tensioning the target belt 12 is included.

  The tension unit 42 stretches the measurement target belt 12 spanned between the cylindrical roll 14 </ b> A and the cylindrical roll 14 </ b> B in the tension direction of the measurement target belt 12. A spool (not shown) for winding a wire 46 such as a piano wire, one end of which is fixed to both of the pair of bearings 18 via a roll 44, and a winding direction of the wire 46 are arranged on the tension portion 42. Alternatively, the motor 42A for rotationally driving in the counter-winding direction is included. The spool not shown is mechanically connected to the motor 42A via a plurality of gears (not shown).

  When the spool (not shown) is rotated by driving the motor 42A, the wire 46 is wound up, and the columnar roll 14A and the columnar roll 14B are moved away from each other, whereby the columnar roll 14A. It is possible to stretch the measurement target belt 12 that is stretched over the cylindrical roll 14B.

  The output unit 38 receives information indicating the flatness of the measurement target belt 12 in a predetermined direction, information indicating the flatness of the entire measurement target belt 12, various information, and the like calculated by the control unit 30. Present to the outside. Examples of the output unit 38 include a display device such as an LCD, a CRT, and an organic EL, a printing device such as a printer, and a communication device such as a network communication port for exchanging data with an external device. For this reason, the flatness measuring apparatus 10 is configured to be able to present various information to the outside of the apparatus.

  The input unit 39 inputs, to the flatness measuring apparatus 10, information indicating the direction and region of the measurement target belt 12 that is a flatness measurement target, and various information such as a flatness measurement instruction. The information indicating the direction to be a plane measurement target includes, for example, information indicating the width direction of the measurement target belt 12, information indicating the circumferential direction of the measurement target belt 12, information indicating a direction inclined by a predetermined angle from the width direction, and the like. is there.

  The area to be measured for the flatness of the measurement target belt 12 includes information indicating an arbitrary position of the measurement target belt 12 and an arbitrary area. As information indicating the arbitrary position, for example, there is information indicating each area obtained by dividing the surface of the measurement target belt 12 facing the projection imaging unit 28 into a plurality of areas in advance.

  Examples of the input unit 39 include a keyboard and a touch panel. In addition, a communication unit device for exchanging data with an external device may be provided as the input unit 39, and the various types of information may be acquired from an external device such as a personal computer via a network or a communication line.

  The control unit 30 controls various devices included in the flatness measuring apparatus 10 and includes a memory 30A. In the memory 30A, various data and a processing routine shown in FIG. 6 to be described later are stored in advance and various data are stored. In addition, the memory 30A previously divides the surface of the measurement target belt 12 stretched between the cylindrical roll 14A and the cylindrical roll 14B, which faces the projection imaging unit 28, into a plurality of areas, and each divided area is divided. Identification information that can be identified and corresponding position information (for example, coordinate information) on the measurement target belt 12 stretched around the cylindrical roll 14A and the cylindrical roll 14B are stored in advance in association with each other.

  This positional information is obtained by, for example, using the projection imaging unit 28 in advance as a reference belt under a condition in which a reference belt having zero flatness is stretched in a state where the cylindrical roll 14A and the cylindrical roll 14B are in the most separated positions. On the basis of the movement position when the reference belt is moved by a predetermined distance in the width direction and the belt movement distance when the reference belt is moved by a predetermined distance in the circumferential direction. The area is divided into a plurality of areas in advance, and the movement distance in the belt width direction of the projection imaging unit 28 and the circumferential movement distance of the reference belt are stored in association with each other as information indicating each divided area. That's fine.

  The circumferential movement distance of the belt is, for example, that a mark is previously provided on the inner circumference side of the belt to be measured, and a sensor is provided at a position where the mark can be detected, and the detection timing of the mark by the sensor is measured. What is necessary is just to make it adjust a movement distance as a movement zero point to the circumferential direction of the object belt 12. FIG. Similarly, the movement distance in the belt width direction is the movement distance in the belt width direction when the projection imaging unit 28 provided so as to be movable in the belt width direction is located at one end side in the width direction. What is necessary is just to prepare.

  Here, when the surface of the measurement target belt 12 stretched by the cylindrical roll 14A and the cylindrical roll 14B is flat and the flatness is “0” over the entire area of the measurement target belt 12, The projection pattern 64 included in the image 62 of the image data obtained by the imaging unit 50, that is, the reference pattern 60 has a circular shape as shown in FIG.

  However, when the flatness of the surface of the measurement target belt 12 is not 0, for example, when the surface of the measurement target belt 12 is distorted in the circumferential direction of the measurement target belt 12, an image 62 of the image data obtained by the imaging unit 50 is obtained. As shown in FIG. 5 (B), the projection pattern 64 included therein has an elliptical shape extending in a direction corresponding to the circumferential direction of the measurement target belt 12 (see the projection pattern 64A in FIG. 5 (B)). . Similarly, when the surface of the measurement target belt 12 in the width direction of the measurement target belt 12 is distorted, the projection pattern 64 included in the image 62 of the image data obtained by the imaging unit 50 is shown in FIG. As shown in FIG. 5, the projection pattern 64B is formed in a shape extending in a direction corresponding to the width direction of the measurement target belt 12 (FIG. 5C).

  In the memory 30A, a reference belt having zero flatness is prepared in advance over the entire outer periphery when stretched between the cylindrical roll 14A and the cylindrical roll 14B, and this reference belt is connected to the cylindrical roll 14A. Image data of an image 62 including a circular reference pattern 60 (see FIGS. 5A and 5B) formed when stretched by the cylindrical roll 14B is stored in advance as reference image data.

  Further, the memory 30A is a value indicated by an international unit for the distortion amount (indicated by the number of pixels) of the projection pattern 64 included in the image 62 of the image data obtained by imaging by the projection imaging unit 28 with respect to the reference pattern 60. The unit conversion table 31 is stored in advance so that it can be converted to

  Since the diameter Db (see FIG. 3) of the circular reference pattern 60 formed on the reference belt is determined, the unit conversion table 31 has a circular reference pattern 60 formed when the flatness is zero in advance. The pixel corresponding to the diameter of the reference pattern 60 included in the image of the reference image data obtained by the projection imaging unit 28 and the data (for example, μm) indicating the actual measurement value and the unit expressed by the international unit of the diameter Db Data indicating the number is stored in advance in association with each other. By storing the unit conversion table 31 in the memory 30A in advance, the amount of distortion (indicated by the number of pixels) of the projection pattern 64 obtained by the projection imaging unit 28 with respect to the reference pattern 60 based on the unit conversion table 31. Can be converted to a numerical value expressed in international units (SI).

  In the present embodiment, the image of the reference image data, the data indicating the diameter Db of the circular reference pattern 60 formed when the flatness is zero, and the image data obtained by the projection imaging unit 28 are used. The data indicating the number of pixels corresponding to the diameter of the reference pattern 60 included in the reference pattern 60 is stored in the memory 30A in advance, but the reference belt stretched between the cylindrical roll 14A and the cylindrical roll 14B is described. Data indicating the diameter Db of the reference pattern 60 and the reference included in the image data obtained by the projection imaging unit 28 for each region obtained by previously dividing the surface of the surface facing the projection imaging unit 28 into a plurality of regions. Data indicating the number of pixels corresponding to the diameter of the pattern 60 may be stored in advance in association with each other. In this way, the flatness can be obtained with higher accuracy.

  Next, the process executed by the control unit 30 when measuring the flatness of the measurement target belt 12 in the flatness measuring apparatus 10 of the present invention will be described.

  The control unit 30 executes the processing routine shown in FIG. 6 every predetermined time, and proceeds to step 100 to confirm that a measurement instruction signal is input from the input unit 39 provided in advance in the flatness measuring apparatus 10. The negative determination is repeated until the determination is made.

  The measurement instruction signal includes a signal indicating a measurement start instruction, information indicating a position at which the flatness of the measurement target belt 12 is measured and a calculation direction of the flatness at the position, and calculation of flatness in the entire region of the measurement target belt 12. Information indicating the direction and information indicating at least one of the information for calculating the flatness over the entire belt 12 to be measured.

  For example, when an LCD is provided as the output unit 38, the measurement instruction signal is input by displaying information prompting the user to input a measurement start instruction on the LCD. Thus, information indicating a measurement start instruction may be input.

  In step 102, tension control is performed with a predetermined load so that the measurement target belt 12 is stretched without slack.

  Specifically, the process of step 102 is performed after determining whether or not the measurement target belt 12 is in a state of being stretched over the cylindrical roll 14A and the cylindrical roll 14B by inputting a detection signal from the detection sensor 99. By controlling the motor 42A so that the wire 46 is wound up until a signal indicating a predetermined pressure is input from the tension detection sensor 47, the belt 12 to be measured can be stretched with a predetermined tension.

  The predetermined pressure can be set to an arbitrary value. For example, a signal indicating a tension is input from the input unit 39 before the flatness is measured, and the signal indicating the input tension is stored in advance. The signal indicating the tension is stored in the memory 30A and the signal indicating the tension is read from the memory 30A when the process of step 102 is executed, and the motor 42A may be controlled so that the tension according to the signal is obtained. If the tension is the same as the tension applied to the measurement target belt 12 when the measurement target belt 12 is mounted on a mounting target apparatus such as an image forming apparatus on which the measurement target belt 12 is mounted, It is possible to determine the flatness of the measurement target belt 12 under substantially the same environment as when the measurement target belt 12 is actually mounted.

  By the process of step 102, the measurement target belt 12 is stretched with a predetermined tension by the cylindrical roll 14A and the cylindrical roll 14B.

  In the next step 104, the light source 52A is controlled to be lit so that the projection pattern 64A is projected onto the measurement target belt 12.

  By the process of step 104, the light emitted from the light source 52A is irradiated onto the surface of the measurement target belt 12 via the surface aperture 52C and the half mirror 54, and the projection pattern 64 is projected onto the measurement target belt 12.

  In the next step 106, a signal indicating an imaging instruction is output to the imaging unit 50 so as to obtain image data of the image 62 including the projection pattern 64 by imaging the projection pattern 64 projected on the measurement target belt 12. To do.

  When a signal indicating imaging is input from the control unit 30, the CPU 74 of the imaging unit 50 acquires image data of the image 62 including the projection pattern 64 on the measurement target belt 12 by imaging and stores the image data in the memory 76. An imaging end signal indicating the end of imaging is output to the control unit 30.

  The control unit 30 repeats negative determination until an imaging end signal is input from the imaging unit 50. If the determination is affirmative, the process proceeds to step 110.

  In step 110, the image data of the image 62 including the projection pattern 64 stored in the memory 76 of the imaging unit 50 is read via the communication unit 78, stored in the memory 30A, and then stored in the memory 76. Delete the image data.

  In the next step 112, the multi-gradation image data stored in the memory 30A by the processing in step 110 is binarized with a predetermined threshold value to generate binarized image data.

  By this binarization process, the image of the multi-gradation image data stored in the memory 30A by the process of step 110 is an area composed of pixels having a density higher than the threshold (that is, an area other than the projection pattern 64). And an area composed of pixels having a density lower than the threshold (that is, an area corresponding to the projection pattern 64). Thus, as an example, as shown in FIG. 7, the image 62 of multi-gradation image data stored in the memory 30 </ b> A by the processing of step 110 is other than the projection pattern 64 composed of pixels having a density higher than the threshold value. Area 63 and an area corresponding to the projection pattern 64 composed of pixels having a density lower than the threshold value.

  In the next step 114, edge detection for detecting pixels (edges) whose brightness difference or density difference from adjacent pixels is equal to or greater than a predetermined value for all pixels of the binarized image data generated by the processing of step 112 above. By performing the processing, the contour of the projection pattern 64 is detected.

  For example, in the image 62 obtained at a predetermined angle of view (effective pixel), the X-axis direction of the image 62 (see FIG. 7) corresponds to the circumferential direction of the measurement target belt 12, and the Y-axis direction of the image 62 (FIG. 7). Reference) corresponds to the width direction of the belt 12 to be measured, and the end 80 (see FIG. 7) of the image 62 is set to a position where both the X coordinate value and the Y coordinate value are 0. What is necessary is just to obtain | require the positional information on each pixel corresponding to the outline of the projection pattern 64A as coordinate information by calculating | requiring the X coordinate value and Y coordinate value of a pixel.

  In the next step 116, the position of the center of gravity of the projection pattern 64 indicated by the contour detected in step 114 (see the center of gravity 72 in FIG. 7) is calculated.

  For the calculation of the center of gravity position, for example, the X coordinate value is obtained by adding binary data of pixels included in the same coordinate in the X-axis direction corresponding to the circumferential direction of the measurement target belt 12 and obtaining and averaging all the coordinates. The position of the center of gravity can be obtained by adding the binary data of the pixels included in the same coordinate on the Y axis and obtaining and averaging all the coordinates to obtain the Y coordinate value.

  In the next step 118, from the coordinates of the centroid 72 (see FIG. 7) obtained in the above step 116 and the coordinates of each pixel constituting the contour of the projection pattern 64, from the centroid 72 to each pixel constituting the contour. The distance is calculated as the number of pixels at a predetermined interval in the circumferential direction.

  The distance from the center of gravity 72 to the coordinates of each pixel constituting the contour is assumed to be a straight line 74 extending in the radial direction from the center of gravity 72, and the straight line 74 is one direction in the Y-axis direction from the center of gravity 72 (FIG. 7). The rotation angle is “0 °” when extending in the direction of arrow Ya), and the straight line 74 is rotated by a predetermined angle around the center of gravity 72 along the circumferential direction of the projection pattern 64. Each time, the distance between the pixel at the position corresponding to the intersection of the straight line 74 and the contour of the projection pattern 64 and the centroid 72 is calculated.

  The predetermined angle may be set in advance so that the rotation angle includes at least 90 degrees, 180 degrees, and 270 degrees, but the straight line 74 is rotated every angle smaller than 90 degrees. Also good.

  In the next step 120, the amount of distortion in the radial direction of the projection pattern 64 included in the image stored in the memory 30A in step 110 with respect to the circular reference pattern 60 stored in advance in the memory 30A is calculated. Are calculated at predetermined intervals along the circumferential direction.

  In the process of step 120, the distortion amount with respect to the reference pattern 60 in the direction corresponding to the predetermined rotation angle of the straight line 74 of the projection pattern 64 is obtained by reading the reference image data from the memory 30A and including the reference image data included in the reference image data. A radial distance in a direction corresponding to the same rotation angle of the pattern 60 and a radial distance corresponding to the same rotation angle and calculated at predetermined intervals along the circumferential direction of the projection pattern 64 in step 118 above. Is calculated as a distortion amount in the rotation angle direction.

  For example, as shown in FIG. 8, the distortion amount in the direction corresponding to the rotation angle 0 ° with respect to the reference pattern 60 of the projection pattern 64 is calculated as the distortion amount Ca, and the distortion amount in the direction corresponding to the rotation angle 90 ° is Calculated as the distortion amount Cb.

  In the next step 122, the distortion amount calculated in step 120 is stored in the memory 30A in association with information indicating the rotation angle.

  The amount of distortion with respect to the reference pattern 60 in an arbitrary direction at a specific position on the measurement target belt 12 is calculated by performing the processing of Step 106 to Step 122 once by turning on the light source 52A and once by the imaging processing by the imaging unit 50. Can do.

  In the next step 124, it is determined whether or not the projection pattern 64 is projected and the projection pattern 64 is imaged from one end to the other end in the width direction of the belt 12 to be measured. If NO, go to step 126.

  The determination in step 124 is, for example, one end in the longitudinal direction of the rail 32 (the width direction of the measurement target belt 12) provided to move the projection imaging unit 28 in parallel to the width direction of the measurement target belt 12 and the other. A sensor (not shown) for detecting the projection imaging unit 28 is provided at the end, and after the detection signal is input from the sensor (not shown) provided on the one end side, the processing of steps 106 to 122 is executed. It can be determined by determining whether or not a detection signal from the sensor on the other end side is input.

  In step 126, the drive unit 36 is controlled so that the projection imaging unit 28 is moved a predetermined distance in the width direction of the measurement target belt 12, and then the process returns to step 106.

  If the determination in step 124 is affirmative, the process proceeds to step 128, in which it is determined whether or not projection of the projection pattern 64 and imaging of the projection pattern 64 have been performed over the circumferential direction of the measurement target belt 12, and Proceeding to step 130, the drive unit 40 is controlled to move the measurement target belt 12 by a predetermined distance in the circumferential direction, and then the process returns to step 106.

  In step 128, for example, a mark is provided in advance on the back surface of the belt 12 to be measured, and a sensor (not shown) for detecting the mark is provided in the flatness measuring apparatus 10, and a detection signal from the previous sensor is received. This can be determined by determining whether or not a detection signal from the next sensor is input to the control unit 30 after being input to the control unit 30.

  If the determination in step 128 is affirmative, the process proceeds to step 132, and the flatness before correction is calculated based on the amount of distortion in the radial direction of each projection pattern 64 stored in the memory 30A.

  More specifically, the flatness is calculated in step 100 with respect to the first direction as the predetermined direction of the predetermined position of the belt 12 to be measured and the second direction different from the first direction. When an instruction signal for calculation is input, the projection pattern 64 included in the image of the image data obtained by imaging in the region corresponding to the predetermined position is based on the distortion amount obtained in step 120 above. The absolute value of the result of subtracting the minimum value from the maximum value of the distortion amount in the opposite directions on the projection pattern 64 corresponding to each of the first direction and the second direction is calculated as the flatness before correction. .

  For example, as shown in FIG. 8, when an instruction signal for obtaining flatness in the Y-axis direction is input for a predetermined region on the measurement target belt 12, the projection patterns 64 corresponding to the Y-axis direction conflict with each other. The absolute value of the subtraction result obtained by subtracting the minimum value from the maximum value of the distortion amount Ca and the distortion amount Cb in each of the Ya direction and the Yb direction is calculated as the pre-correction flatness.

  Similarly, the pre-correction flatness in the X-axis direction can be calculated.

  As the flatness calculation, in step 100, an instruction signal for calculating the flatness is input for the first direction and the second direction different from the first direction in the entire region of the belt 12 to be measured. In the case of being performed, distortions in directions opposite to each other corresponding to each of the first direction and the second direction of each of the plurality of projection patterns 64 obtained by executing the processing of Step 100 to Step 130 described above. By obtaining the absolute value of the value obtained by subtracting the minimum value from the maximum value of the quantity, the flatness before correction in the first direction and the second direction is obtained.

  Further, as the calculation of the flatness, when an instruction signal for calculating the flatness is input over the entire belt to be measured 12 in the above step 100, the above steps 100 to 130 are executed. The absolute value of the value obtained by subtracting the minimum value from the maximum value among the distortion amounts calculated in each of the plurality of projection patterns 64 obtained by the above is obtained as the pre-correction flatness of the entire measurement target belt 12.

  In this embodiment, the case of obtaining the flatness in two directions as a plurality of directions will be described. However, the flatness in three or more directions may be obtained. Even in the case of obtaining flatness in three or more directions, it is possible to obtain flatness in three or more directions by performing the above-described processing for each direction.

  In the next step 134, the pre-correction flatness obtained in step 132 based on the unit conversion table 31 stored in the memory 30A is converted into the international unit (SI). Is converted to a numerical value represented by.

  That is, based on the unit conversion table 31, a value and a unit expressed in an international unit corresponding to one pixel are obtained. Next, since the flatness before correction obtained in step 132 is a value indicated by the number of pixels, the value indicating flatness before correction obtained in step 132 is converted into data indicating international units. .

  A value indicating an arbitrary area on the measurement target belt 12, an arbitrary plurality of directions in an arbitrary area, an arbitrary plural directions in the entire measurement target belt 12, or a flatness of the entire measurement target belt 12 by the process of step 134. And the unit can be determined.

  In the next step 136, each flatness obtained by the conversion to the international unit in step 134 is output to the output unit 38, and then this routine is terminated.

  As described above, according to the flatness measuring apparatus 10 of the present invention, a projection pattern is obtained by irradiating a circular pattern on the measurement target belt 12 and imaging the projection pattern projected on the measurement target belt 12. The image data is obtained, and the flatness in an arbitrary direction is obtained based on the radial distortion amount with respect to the circular reference pattern of the projection pattern included in the obtained image data image. The flatness in a plurality of directions of the measurement target belt 12 can be easily obtained with a simple configuration.

  Further, the projection unit 52 for projecting the projection pattern and the imaging unit 50 for imaging the projection pattern can be integrally moved from one end to the other end in the width direction of the measurement target belt 12. In addition, since the measurement target belt 12 can be rotated in the circumferential direction, the flatness in a plurality of directions can be easily obtained with a simple configuration over the entire surface of the measurement target belt 12. Flatness in any of a plurality of directions can be easily obtained with a simple configuration.

  In addition, when 500 pixels correspond to one side of the angle of view of the image obtained by the imaging unit 50, when the angle of view is 10 mm × 10 mm, the international unit corresponding to one pixel is 20 μm. When the imaging unit 50 having an effective pixel number of 500 × 500 pixels is used and the angle of view is adjusted so that the diameter of the projection pattern is less than 10 mm, a resolution of 20 μm can be obtained. Therefore, it can be said that the flatness can be obtained accurately with a simple configuration.

[Test example]

  An intermediate transfer belt (polyimide resin intermediate transfer belt having a width of 330 mm and a peripheral length of 948 mm) used in an electrophotographic image forming system was prepared as the measurement target belt 12. This intermediate transfer belt is preliminarily dispersed with carbon black to impart conductivity, and has a black and glossy surface.

  Such an intermediate transfer belt is stretched on the flatness measuring apparatus 10 of the present invention on the cylindrical roll 14A and the cylindrical roll 14B constituted by stainless steel rolls (φ30 mm). .It was stretched so as to have a load of 2N.

  Next, a light source 52A is formed on the surface of the intermediate transfer belt at a position 200 mm from the end in the stretching direction of the intermediate transfer belt stretched by the cylindrical roll 14A and the cylindrical roll 14B toward the circumferential direction of the intermediate transfer belt. A projection pattern having a cross-sectional shape of a light beam having a diameter of 5 mm was projected onto the intermediate transfer belt from a projection unit 52 using a surface aperture 52C having a circular hole 52D using white light. This projected pattern was imaged using Keyence CV-2000 as the imaging unit 50.

  Next, binarization processing is performed on each image including the projection pattern obtained by imaging (see FIG. 9A). After binarization processing, the center of the projection pattern is obtained, and the projection pattern is calculated from the center of gravity. The distance to the contour is rotated by 90 degrees with the direction corresponding to the width direction being 0 degrees (see FIG. 9B), and the distance from the pixel corresponding to each of the four locations on the contour to the center of gravity is obtained. It was. Next, the difference between the distance from the calculated center of gravity to the pixel corresponding to each of the four locations on the contour and the radius of the reference pattern was determined as a distortion amount. This distortion amount was converted based on the unit conversion table 31 so as to be an international unit. For example, when one pixel corresponds to 20 μm, the distance for 50 pixels is converted to 1 mm.

  The above-described imaging processing, and the calculation of the distortion amount based on the projection pattern of the image obtained by imaging and the conversion to the international unit amount are performed by moving the projection imaging unit 28 by 10 mm in the width direction of the intermediate transfer belt. Done about the area. Further, after the intermediate transfer belt was moved 10 mm in the circumferential direction, the projection imaging unit 28 was moved by 10 mm in the width direction of the intermediate transfer belt in the same manner as described above for each region.

  The results are shown in FIG.

  As shown in FIG. 10, in the projection pattern projected on the area 80 on the intermediate transfer belt, which corresponds to the case where the number of movements in the axial direction is one and the number of movements in the circumferential direction is one, the intermediate transfer The amount of distortion in the opposite direction of the width direction (Y direction) of the belt is -1.28 mm and -1.00 mm, respectively. Further, the amounts of distortion in the opposite directions in the circumferential direction (X direction) of the region 80 of the intermediate transfer belt are −0.71 mm and −1.02 mm, respectively.

  Therefore, the flatness in the circumferential direction (X direction) of the region 80 is 0.28 mm from the absolute value of the difference between the maximum value “−1.00 mm” and the minimum value “−1.28 mm” of the distortion amount, and the width The flatness in the direction (Y direction) is 0.31 mm from the absolute value of the difference between the maximum distortion amount “−0.71 mm” and the minimum distortion amount “−1.02 mm”.

  Further, as shown in FIG. 10, when the number of movements in the circumferential direction is one time, when it is the second time, when calculating the flatness in the width direction of the intermediate transfer belt at each position, the projection imaging unit The maximum value of distortion amounts in the opposite directions in the Y direction calculated based on the projection pattern obtained for each region by moving 28 by 10 mm in the width direction of the intermediate transfer belt is “0.19 mm” ( (The amount of distortion at the time of the 29th measurement in the width direction), and the minimum value is “−1.28 mm” (the amount of distortion of the measured value of one interface in the width direction). The flatness in the width direction at the predetermined position is 1.47 mm.

It is a schematic block diagram which shows typically the flatness measuring apparatus of this invention. It is a schematic diagram which shows the roll periphery where the load is applied in the flatness measuring apparatus of this invention. It is a schematic diagram which shows a part of electrical structure of the flatness measuring apparatus of this invention. It is a schematic diagram which shows the measuring object belt of the state stretched by a pair of roll. (A) is a schematic diagram which shows the projection pattern and reference | standard pattern which are included in the image obtained by imaging. (B) and (C) are schematic diagrams showing a reference pattern and a projection pattern distorted in a predetermined direction. It is a flowchart which shows the process performed in the control part of the flatness measuring device of this invention. It is a schematic diagram which shows the projection pattern contained in the image obtained by imaging. It is a schematic diagram which shows an example of the projection pattern and reference | standard pattern which are included in the image obtained by imaging. (A) is a schematic diagram illustrating binarization processing, and (B) is a schematic diagram illustrating contour extraction processing. It is a part of data which shows the distortion amount obtained in the test example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flatness measuring apparatus 12 Measuring object member 28 Projection imaging part 30 Control part 31 Unit conversion table 36 Drive part 38 Output part 39 Input part 42 Stretching part 50 Imaging part

Claims (2)

Projection means for projecting a circular pattern onto the surface of the measurement target member;
Imaging means for acquiring image data indicating a projection pattern projected on the measurement target member by imaging;
Distortion amount calculating means for calculating a radial distortion amount of a projection pattern of image data acquired by the imaging means with respect to a predetermined reference pattern similar to the circular pattern at predetermined intervals in the circumferential direction; ,
Based on the absolute value of the difference between the maximum value and the minimum value of the strain amounts in the opposite directions of the strain amounts calculated by the strain amount calculation means, the direction of the measurement target member corresponding to the opposite directions Flatness calculating means for calculating the flatness of
A flatness measuring device comprising: Project a circular pattern onto the surface of the measurement target member,
Obtaining image data indicating a projection pattern projected on the measurement target member by imaging,
The amount of distortion in the radial direction of the projection pattern of the acquired image data with respect to a predetermined reference pattern similar to the circular pattern is calculated at predetermined intervals in the circumferential direction,
Based on the absolute value of the difference between the maximum value and the minimum value of the calculated strain amounts in the directions opposite to each other, the flatness in the direction of the measurement target member corresponding to the directions opposite to each other is calculated. ,
Flatness measurement method.

Images