JP2006215002A - Belt slip measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely measure a belt slip without being affected by an error factor of a drive unit comprising a driving roller, a driven roller and a belt, by contriving the belt. <P>SOLUTION: This belt slip measuring instrument measures the slip generated between the belt driven by the driving roller and the driven roller, and includes (1) a pattern formed of a material not fixed to the belt, on a face of the belt contacting with the rollers, (2) an optical sensor for measuring a shape of the pattern on the belt passed through the rollers under a driving condition, and (3) an analyzer for analyzing a measured value from the optical sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-accuracy belt slip measuring device for measuring slip with respect to a roller such as an intermediate transfer belt, a photosensitive belt, or a paper conveying belt mounted on an image forming apparatus, and the like. Can be used for evaluation. This belt slip measuring device is not limited to a belt mounted on an image forming apparatus, and can be applied to a case where a general belt slip state is detected.

In an electrophotographic quadruple tandem full-color image forming apparatus, etc., the intermediate transfer belt drive control mounted on it, and in the image forming apparatus, a photosensitive belt drive control, a paper transport belt drive control, etc. It has many components that require stability of the conveyance speed.
In these components, it is ideal that the belt is driven constantly, but slippage is locally generated between the belt and the roller due to fluctuations in the rotational speed of the driving roller and geometrical tolerances between the driven roller and the belt. It is known to occur.

Based on FIG. 1, the operation of the image forming / transfer mechanism unit 10 in the four-drum tandem full-color image forming apparatus will be described. Electrostatic images are formed on the respective photoconductors 11a to 11d, and become visible images (toner images) with toner. The toner images are transferred to the intermediate transfer belt 12 by the photoconductors 11 a to 11 d and the first transfer portions 13 a to 13 d of the intermediate transfer belt 12. The intermediate transfer belt 12 is held and driven by a driving roller 14 and driven rollers 15a and 15b. The toner image transferred to the intermediate transfer belt 12 moves and is transferred to the paper 17 by the second transfer unit 16 to form an image on the paper 17.
In the quadruple tandem system, there are four photoconductors 11a to 11d, and different color images are formed on each photoconductor (cyan, magenta, yellow, black). This color image is superimposed on the intermediate transfer belt 12 to form a full-color image, which is finally transferred to the paper 17.

In particular, the characteristic to be measured in the present invention is slip generated between the intermediate transfer belt 12 and the rollers 14, 15a, 15b. It is known that the occurrence of such slip causes a phenomenon that the overlapping positions of the four colors are irregularly shifted. It is important to accurately grasp the mechanism of the slip itself as information to suppress this.
This slip occurs in a very short time, and the slip amount is very small. Further, since color alignment requires alignment in units of μm, it is necessary to accurately capture a small amount of slip.
The actual slip is expected not only to occur simultaneously in the entire belt, but also to a micro-slip phenomenon that occurs partially (locally). That is, even if the relative speed between the belt and the roller is detected at the end of the belt, not all slips that have occurred can be covered. Therefore, it can be expected that by accurately grasping the slipping range and position, it will lead to the elucidation of the geometric slip mechanism of the rollers and belts.

In measuring this characteristic, the following items can be cited as error factors.
(1) Height fluctuation when driving the belt If fluctuations in the belt thickness or eccentricity of the roller itself occur, the distance from the roller center to the belt surface will fluctuate.
(2) Roller surface speed fluctuation If the belt rotates at the same speed as the roller, the belt does not slip. However, the surface speed of the roller is not constant due to fluctuations in the speed of the motor that drives the roller, eccentricity of the roller itself, and the like. That is, even if only the belt surface speed is detected, a very small slip cannot be detected, and only the relative speed with respect to the roller or the positional deviation can be detected.
(3) Belt meandering phenomenon The belt meanders in a direction perpendicular to the feed direction by driving. Although this meandering is generally a low frequency, it affects fine position measurement.
Incidentally, as the material of the intermediate transfer belt 12, polyethylene terephthalate, polycarbonate, and polyimide are known, and transparent materials such as polyvinylidene fluoride are often used.

As a conventional technique relating to slip measurement of a belt roller (pulley) which is an object of the present invention, a technique described in Japanese Patent Application Laid-Open No. 2000-131055 (a method for measuring a minute slip of a friction transmission belt) has been proposed.
In this publication, the speed fluctuation of the driving roller or driven roller that drives the belt and the speed fluctuation of the belt driven by the belt are simultaneously measured, and the difference is calculated from the measured values of both to calculate the slip of the belt. Methods for determining quantity and time have been proposed. In particular, by using a non-contact laser Doppler measurement device or the like as a measurement method, minute fluctuations are captured without applying a load to the belt.
However, in such a measurement method, even if the presence / absence of slip and the occurrence time can be specified, the generation site and generation range cannot be specified, and information for elucidating the slip generation mechanism cannot be obtained. That is, there is a drawback that it is difficult to obtain data necessary for parameter design for reducing slip.

Moreover, although it is not a well-known document, as a prior application (Japanese Patent Application No. 2004-195661) of the applicant of the present application, the speed is measured by detecting position detection patterns formed on the belt and the roller using a camera. Thus, a method for detecting a slip from the difference has been proposed.
In the slip detection method of the prior application, both speeds can be detected at the same time by the same measuring instrument (camera), so that the measurement timing can be completely matched, and the microslip in a minute region can be detected by increasing the camera magnification. There are excellent advantages such as. However, this slip detection method has a limitation that the belt must be a transparent member and cannot be applied to any drive system.
JP 2000-131055 A

  An object of the present invention is to make it possible to perform highly accurate belt slip measurement without being affected by these error factors by devising the belt in consideration of the above three error factors. It is.

The solution to the above problem is based on forming a pattern with a material that is not fixed to the belt on the surface of the belt that contacts the roller, and measuring the change in the pattern shape after the pattern has passed the roller. Yes.
[Solution 1] (corresponding to claim 1)
Solution 1 taken to solve the above problems is based on a belt slip measurement device that measures a slip generated between a belt driven by a driving roller and a driven roller and the roller. A) to (c).
(A) A pattern formed of a material not fixed to the belt on the surface of the belt that contacts the roller.
(B) An optical sensor that measures the shape of the pattern on the belt that has passed through the roller in a driving state.
(C) An analysis device for analyzing the measurement value of the optical sensor.

[Operation]
After the pattern formed on the belt passes through the roller, the shape of the pattern is measured by an optical sensor (such as a CCD camera or an optical sensor that detects the amount of reflected light in a minute area), and the measured value (image or amount of reflected light). ) (The comparison between the specific dot size of the pattern and the standard dot size, or the change in the amount of reflected light in time series, etc.) can be measured for the belt slip.
In this belt slip measuring device, the slip occurrence site is not directly measured, but a method of detecting a slip result is detected. For example, a direct slip occurrence site such as a roller position fluctuation or a roller surface speed fluctuation at the time of belt driving is detected. It is not affected by the behavior of the drive system that may cause errors in measurement. In addition, since the displacement and elongation of the pattern formed on the belt are detected, the measurement can be performed after the slip phenomenon occurs, not in real time.

[Embodiment 1] (corresponding to claim 2)
Embodiment 1 is to provide the belt slip measuring device of Solution 1 described above, comprising ink jet printing means for forming a pattern on the belt, and forming the pattern simultaneously with driving of the belt.
[Operation]
Since the pattern can be formed on the belt by the ink jet head, the pattern can be formed in a state where the belt is set in the driving device. This eliminates the trouble of removing the belt from the drive device and assembling the drive device.

[Embodiment 2] (corresponding to claim 3)
Embodiment 2 is that the pattern formed on the belt in the belt slip measuring device of Solution 1 or Embodiment 1 is a parallel line pattern parallel to the axial direction of the roller.
[Operation]
Since the pattern on the belt is a parallel line pattern parallel to the axial direction of the roller, the pattern can be measured with an optical sensor even if the belt swings in the direction perpendicular to the feed direction when the belt is driven (the belt meandering phenomenon occurs). Nothing will happen.

[Embodiment 3] (corresponding to claim 4)
Embodiment 3 is that, in the belt slip measuring apparatus according to Solution 1 or Embodiment 1, the pattern formed on the belt is a dot row oblique to the feeding direction of the belt.
[Operation]
Since the pattern on the belt is a dot row oblique to the belt feeding direction, the dot-to-dot pitch in the belt feeding direction can be reduced.

[Embodiment 4] (corresponding to claim 5)
Embodiment 4 is that, in the belt slip measuring apparatus according to Solution 1 or Embodiment 1, the pattern formed on the belt is a line pattern oblique to the feeding direction of the belt.
[Operation]
Since the pattern on the belt is a line pattern that is oblique to the belt feed direction, there is no dot-to-dot break in the belt feed direction, and no matter where the slip occurs, the pattern is affected. It will be.

[Solution 2] (corresponding to claim 6)
The solution 2 taken in order to solve the above problem is based on the following requirements (on the premise of a belt driven by a driving roller and a driven roller and a belt slip measuring device for measuring a slip generated between the rollers) D) to (g).
(D) A pattern formed of a material not fixed to the belt on the surface of the belt that contacts the roller.
(E) A first imaging device that photographs the pattern on the belt before it passes the roller.
(F) A second imaging device that images the pattern after the pattern on the belt has passed the roller.
(G) An analysis device for analyzing pattern images acquired by the first and second imaging devices.

[Operation]
The pattern on the belt before passing through the roller is photographed by the first photographing device, the pattern on the belt after passing through the roller is photographed by the second photographing device, and photographed by the first and second photographing devices. The belt slip state is measured by analyzing each of the images performed by the analysis device.
In this belt slip measuring device, the pattern shape can be acquired in advance before the pattern formed on the belt passes through the roller, so check the difference from the pattern shape after the pattern passes through the roller can do.

[Embodiment 5] (corresponding to claim 7)
Embodiment 5 is the belt slip measurement device of Solution 2 described above, wherein the analysis device calculates the pattern size from the pattern image acquired by the first imaging device and the pattern image acquired by the second imaging device. It has a function of calculating the pattern size and a function of calculating the difference between the two pattern sizes in time series.
[Operation]
The analysis device calculates a pattern size from each image captured by the first and second imaging devices, and calculates a belt slip amount by comparing these pattern sizes. In particular, by using an inkjet or the like for pattern formation, it is possible to measure a good slip state even when the accuracy of the pattern is poor.

[Embodiment 6] (corresponding to claim 8)
Embodiment 6 is a reference marker that serves as a relative position reference between the pattern image acquired by the first imaging device and the pattern image acquired by the second imaging device in the belt slip measurement device of Solution 2 or Embodiment 5 described above. Is formed on the belt.
[Operation]
Since the pattern is formed on the belt and the slip amount is measured with the reference marker formed, it is possible to reliably correspond the pattern shape before passing the roller and the pattern shape after passing the roller. it can.

[Solution 3] (Corresponding to Claim 9)
Solution means 3 taken to solve the above problems is based on a belt slip measurement device that measures the slip generated between the belt driven by the driving roller and the driven roller and the roller. H) to (nu).
(H) A pattern formed of a material not fixed to the belt on the surface of the belt that contacts the roller.
(I) An optical sensor that detects the amount of light reflected from a minute region of the pattern on the belt that has passed through the roller in the driving state.
(N) An analysis device for analyzing a change in reflected light amount in time series detected by the optical sensor.
[Operation]
Using an optical sensor that detects the amount of reflected light as an optical sensor, the amount of reflected light is detected in a time series from a minute region of the pattern on the belt, and the belt slip state is measured by analyzing the change in the amount of reflected light. This optical sensor is very inexpensive and small as an optical sensor.

[Embodiment 7] (corresponding to claim 10)
Embodiment 7 is a belt slip measuring device according to Solution 3 described above, wherein the analysis device is equipped with a correction table for calculating a belt slip amount corresponding to a change in the amount of reflected light, and belt slip using this correction table. Is to calculate the quantity.
[Operation]
Using the correction table mounted on the analysis device, the measurement value obtained by the optical sensor can be easily converted into the slip amount.

The effects of the present invention are summarized for each main claim as follows.
(1) The invention according to claim 1 Since it is a system that detects the slipped result instead of directly measuring the site where the slip occurs, for example, the occurrence of direct slip such as roller position fluctuation or roller surface speed fluctuation when driving the belt. The slip phenomenon can be measured without being affected by the behavior of the drive system that may cause an error when measuring the part.
In addition, since the displacement and elongation of the pattern formed on the belt are detected, it is possible to measure with high accuracy over time after the slip phenomenon occurs.
(2) The invention according to claim 2 Since the pattern can be formed in a state where the belt is set in the driving device, there is no trouble of removing the belt from the driving device or assembling the driving device. Stable belt slip measurement can be performed without causing a drive failure due to an assembly failure to the apparatus.

(3) Invention of Claim 3 Since the pattern on the belt is a line pattern parallel to the axial direction of the roller, even if the belt fluctuates in the direction perpendicular to the feed direction when the belt is driven (even if the belt meander phenomenon occurs) ), The pattern cannot be measured by the optical sensor, and stable belt slip measurement can be performed.
(4) The invention according to claim 4 Since the pattern on the belt is a row of dots oblique to the belt feeding direction, the dot-to-dot pitch in the belt feeding direction can be reduced. A slip phenomenon that occurs instantaneously in the region can also be detected without omission.

(5) Invention of Claim 5 Since the pattern on the belt is a line pattern oblique to the belt feeding direction, there is no dot-to-dot break in the belt feeding direction, and slip occurs at any position. However, since it affects the pattern, even a slip phenomenon occurring in any minute region can be detected completely.
(6) Invention of Claim 6 Since the pattern shape can be acquired in advance before the pattern formed on the belt passes through the roller, the difference from the pattern shape after the pattern passes through the roller. By checking this, the slip state can be measured more accurately. Specifically, even if the pattern formed on the belt is defective, for example, the size is not uniform, the shape can be acquired in advance, so that the error factor can be eliminated.

(7) The invention according to claim 7, wherein the analysis device calculates a pattern size from each image captured by the first and second imaging devices, and calculates a belt slip amount by comparing the pattern sizes. Therefore, even when the accuracy of the pattern formed on the belt is poor, the slip state can be measured more accurately.
In particular, even when it is difficult to form a pattern with high accuracy using an inkjet or the like for pattern formation, it is possible to measure the slip amount with high accuracy.
(8) The invention according to claim 8 Since the pattern is formed on the belt and the belt slip amount is measured in a state where the reference marker is formed, the pattern shape in the stage before passing through the roller and after passing through the roller It is possible to reliably correspond to the pattern shape. As a result, even in continuous measurement with a continuous dot pattern, pattern alignment before and after passing through the rollers does not go wrong, and the slip state can be measured more accurately and continuously.

(9) Invention of Claim 9 Using an optical sensor for detecting the amount of reflected light as an optical sensor, the amount of reflected light is detected in time series from a minute region of the pattern on the belt, and the change in the amount of reflected light is analyzed to analyze the belt slip. Measure state. Since this optical sensor is very inexpensive and small as an optical sensor, not only the entire measuring apparatus can be simply configured, but also a plurality of optical sensors can be operated simultaneously.
(10) The invention according to claim 10 The measurement value obtained by the optical sensor can be easily converted into the slip amount by using the correction table mounted on the analysis apparatus, so that the measurement can be performed regardless of the simple apparatus. The slip amount can be converted and detected in real time. Specifically, while continuously measuring with the drive system including the belt and rollers in an operating state, the slip amount when a predetermined load is applied to the drive system is converted and detected in real time. be able to.

  The purpose is to make it possible to perform highly accurate belt slip measurement without being affected by the error factors of the driving device consisting of the driving roller, driven roller and belt, and to form a pattern on the belt contact surface This was realized by an original configuration in which a pattern shape change after the pattern was passed through the roller was measured.

Example 1 (corresponding to claims 1 and 3 to 5) of the present invention will be described with reference to FIGS. 2-1 to 2-6. Fig. 2-1 is a schematic diagram of the belt slip measuring device, Fig. 2-2 is a pattern image of the belt slip measuring device, Fig. 2-3 is slip measurement data by the belt slip measuring device, and Fig. 2-4 to Fig. 2-6. Is a pattern image in the belt slip measuring device.
As shown in FIG. 2A, the belt slip measuring device 20 according to the first embodiment includes a belt 21 to be measured and a roller 22 that holds the belt 21, and a side in contact with the roller 22. The pattern 23 is formed on the surface of the belt 21 and the roller 22 is rotated to change the shape (shape change) of the pattern 23 at a position after the pattern 23 is conveyed (passed) on the roller 22. An optical sensor 24 for detection is installed, and an analysis device 25 for analyzing a measurement value output from the optical sensor 24 is provided.

The pattern 23 is made of a material that does not adhere to the belt 21, for example, a highly viscous liquid (such as ink) or powder. As this high-viscosity liquid, a gravure ink or the like is suitable using a pigment-based color material. Since the viscosity of offset ink or the like is too high, when it is used, it is necessary to knead it sufficiently to make it in a low viscosity state. As the powder, particles of about 5 to 30 μm such as toner are suitable. The pattern 23 is formed in a minute range with respect to the entire area and the coating amount is made as thin as possible for the above reason so as not to affect the slip phenomenon generated between the belt 21 and the roller 22. The pattern shape 23 is not applied to the solid, but a boundary portion between the application region and the region other than the application region is present, such as an independent dot. As a method of forming the pattern 23, for example, a screen printing method or the like can be used. In addition, by applying this, it is possible to use a method in which a mount with a hole is placed in close contact with the belt, the powder is dropped from above or ink is applied, and then the mount is gently released.
As the color of the pattern 23, a color that provides a high contrast with the color of the belt 21 is selected. Also, if the interval between the dots of the pattern is narrow, if the pattern forming material is a liquid such as ink, it will be crushed by the roller after passing through the roller, and it will not be possible to detect the slip state by overlapping with the adjacent dot. It is necessary to take a distance.

The optical sensor 24 detects that the pattern 23 is conveyed (passed) between the belt 21 and the roller 22 and the shape of the pattern 23 is changed. A line CCD camera or the like that photographs in a direction perpendicular to the direction is used. Alternatively, an optical sensor that detects the optical reflectance at one point on the belt 21 may be simply used.
When photographing with the CCD camera while the belt 21 is being fed, it is necessary to make the shutter speed sufficiently higher than the feeding speed of the belt 21 so that the photographed image does not flow. For example, if the belt feed speed is 1000 mm / s and the slip amount to be detected is 1 μm, the shutter speed needs to be about 1 / 100,000 seconds.
On the other hand, this is not the case when the pattern 23 passes the roller 22 and then the conveyance of the belt 21 is stopped to take an image.

  If the optical sensor 24 is a CCD camera, the analysis device 25 has a function of recording and displaying a photographed image and can observe the shape of the pattern 23, and is generally called an image processing device. And can be substituted by a personal computer. If the optical sensor 24 is an optical sensor, the analyzing device 25 has a function of recording / displaying a time-series amount of reflected light.

A slip measuring method in the belt slip measuring apparatus of the first embodiment will be described below.
FIG. 2-2 (a) shows a pattern image before passing through the roller 22, and FIG. 2-2 (b) shows a pattern image after passing through the roller 22. As shown in FIG. 2-2 (a), dots 27 (using printing ink) are formed in an orderly manner before passing through the roller 22. When the dots 27 pass between the roller 22 and the belt 21, as shown in FIG. 2-2 (b), the dots 27 are crushed and photographed. Further, when a local slip occurs between the roller 22 and the belt 21, the shape of the collapsed dot changes like the slip generation portion 28. The slip amount can be calculated by measuring the size of the shape (dot size in the belt feeding direction).
Slip amount = specific dot size−standard dot size The slip amount is calculated in the analyzer 25 using an image acquired by a camera.
By performing the above processing for each dot formed at equal intervals on the pattern, as shown in FIG. 2-3, the slip behavior in time series can be obtained.

Next, various patterns formed on the surface of the belt 21 on the side in contact with the roller 22 will be described with reference to FIGS. 2-4 to 2-6.
The pattern shown in FIG. 2-4 is formed by a line pattern perpendicular to the feeding direction of the belt 21. When slip measurement is performed using this line pattern, even if a belt meandering phenomenon (fluctuation in the roller axis direction) occurs, there is no possibility that the measurement area of the optical sensor 24 will deviate. In such a line pattern, the line pattern width becomes large at the portion where the slip occurs.

  The pattern shown in FIG. 2-5 is formed as a dot pattern oblique to the feeding direction of the belt 21. When slip measurement is performed using this dot pattern, the dot pitch can be set finely with respect to the feeding direction of the belt 21. However, when the dot pattern is used, a single-point optical sensor or the like cannot be used as the optical sensor 24, but a CCD camera or the like that can measure simultaneously in a direction perpendicular to the belt feeding direction. It is necessary to use a sensor that can measure a wide area.

Also, the pattern shown in FIGS. 2-6 is formed as a line pattern diagonal to the feed direction of the belt 21. When slip measurement is performed using this diagonal line pattern, the dot pitch can be set finely with respect to the feeding direction of the belt 21. However, when the oblique line pattern is used, the optical sensor 24 cannot use a single-point measurement optical sensor or the like, and needs to use a sensor capable of wide-area measurement such as a CCD camera.
In the measurement of the slip amount by the oblique line pattern, the dot size and the line pattern width cannot be measured. Therefore, the detection is performed based on the bulge amount of the pattern bulge portion 29 described in FIG. When slip occurs, the amount of swelling increases as shown in FIG.
As for the dimensions of the pattern formed on the belt, the dimensions cannot generally be determined depending on the required accuracy as the image forming apparatus (target image quality) and product specifications (linear speed, etc.) As an example, when assuming that the slip amount to be detected is 4.23 μm (in a 600 dpi machine, 1/10 of one pixel is the slip amount to be detected), the dimensions of each pattern, In consideration of camera specifications (photographing magnification) and optical sensor (single-point measurement) specifications, detection is possible if the pattern width is 100 μm and the pattern pitch is 400 μm. Such pattern dimensions are the same regardless of the pattern shape such as diagonal lines and lines. The pitch value is a distance for preventing contact with an adjacent pattern due to pattern bleeding, and needs to be about three times the pattern width, and depends on the pattern forming material.

Example 2 (corresponding to claims 2 to 5) of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of a belt slip measuring device.
As shown in FIG. 3, the belt slip measuring device 30 according to the second embodiment is similar to the belt slip measuring device according to the first embodiment (see FIG. 2A). It is what I do.
In the first embodiment, the pattern is formed on the belt by using the screen printing method. However, the pattern is formed on the belt set on the driving system such as a roller (on the inner belt in contact with the roller). Since it is difficult to form the pattern, it is necessary to set the belt in the drive system after forming the pattern with the belt removed.

On the other hand, the belt slip measuring device 30 according to the second embodiment is upstream in the direction in which the belt 31 is fed to the roller 32 side so that the pattern can be formed with the belt 31 set in the drive system. The inkjet head 35 is installed. The ink-jet head 35 forms dot patterns 33 on the belt 31 at regular intervals in time, and the pattern 33 is measured by the optical sensor 34 after the dot pattern 33 has passed the roller 32.
As the pattern 33 formed by the inkjet head 35, the pattern shown in FIGS. 2-2 and FIGS. 2-4 to 2-6 can be used as in the case of the first embodiment.

A third embodiment (corresponding to claims 6 to 8) of the present invention will be described with reference to FIGS. 4-1 and 4-2. FIG. 4A is a schematic diagram of the belt slip measuring device, and FIG. 4B is a pattern image of the belt slip measuring device.
As shown in FIG. 4A, the belt slip measuring device 40 of the third embodiment is a pre-roller photographing device 44 that measures the pattern 43 before the pattern 43 on the belt 41 passes the roller 42. And a post-roller imaging device 45 that measures the pattern 43 after the pattern 43 has passed the roller 42. The analysis device 46 receives image signals from both the pre-roller photographing device 44 and the post-roller photographing device 45.
According to the configuration of the third embodiment, when the measurement is started by driving the roller 42, the shape of the pattern 43 before entering the roller 42 can be easily measured.

The pattern 43 on the belt 41 is formed using screen printing, ink jet, or the like. The formed pattern size (size A) is calculated by the analysis device 46 from the image photographed by the photographing device 44 before passing through the roller. This value is recorded in the analyzer 46 as a correction value. Next, the pattern size (size B) of the pattern 43 that has passed through the roller 42 is calculated by the analysis device 46 from the image captured by the imaging device 45 after passing through the roller.
Finally, the analysis device 46 calculates the slip amount by the following calculation formula (1).
Slip amount = size B−size A (1)
However, the above calculation formula (1) is for the case where the pattern 43 is formed of a material such as powder that is not crushed by the roller pressure. It is also necessary to do.

An example of the pattern 43 used in the belt slip measuring device (see FIG. 4-1) of the third embodiment will be described with reference to FIG. In this pattern example, one or more reference markers 48 are provided on the side (perpendicular to the belt feed direction) of the slip amount detection pattern at equal intervals in the case of a plurality. The dimensions of this pattern are the same as those in the first embodiment, and the pattern width is 100 μm and the pattern pitch is 400 μm. In this case, a photographing device (CCD camera) is used as the optical sensor.
When the analysis device 46 analyzes the image data output from the photographing devices 44 and 45 installed at positions before and after passing through the roller 42, the position of the reference marker 48 of this pattern is also detected at the same time. The When the slip amount is calculated by applying the calculation formula (1), the pattern sizes are matched based on the position of the reference marker 48. That is, when the pattern size is continuously measured and the respective slip amounts are calculated, it is necessary to match the pattern size before passing through the roller 42 and the pattern size after passing through the roller 42. Therefore, the detection timing of the reference marker 48 is used.

Embodiment 4 (corresponding to claims 9 and 10) of the present invention will be described with reference to FIGS. 5A is a schematic diagram of an optical sensor of the belt slip measuring device, FIGS. 5-2 and 5-3 are measurement data acquired by the optical sensor of the belt slip measuring device, and FIG. 5-4 is a belt slip measuring device. It is a conversion table graph.
The belt slip measuring device according to the fourth embodiment is shown in FIG. 5-1 as an optical sensor in the belt slip measuring device according to the first embodiment or the second embodiment (see FIG. 2-1 or FIG. 3). An optical sensor 54 that measures the amount of light reflected from such a measurement surface is used.

The optical sensor 54 emits light from the light emitting unit 55 to the measurement surface 51a on the belt 51 and detects the amount of reflected light by the light receiving unit 56. The reading area is limited by a lens or the like (the light receiving unit side). ) Or limiting the illumination light (on the light emitting unit side), the measurement area can be made minute.
As an indication of the area to be read, about 1/10 or less of the pattern size 57 and the pattern pitch 58 of the pattern 53 is desirable. If the size is too large, it will not be possible to detect variation in the density of the pattern, and if it is too narrow, dust on the belt will become a noise component and cause a measurement error. Since the illumination light of the optical sensor 54 needs to be narrowed down to a very small area, it is imaged by a lens or the like, or laser light or the like is used.
The dimensions of the pattern 53 are the same as those in the first embodiment, and the pattern width is 100 μm and the pattern pitch is 400 μm.

  An example of measurement data acquired by the optical sensor 54 is shown in FIG. In this case, the horizontal axis represents time, the vertical axis represents the amount of reflected light, the measured color of the belt 51 is black, and the color of the pattern 53 is white. A waveform having a constant period is obtained according to the period of the pattern 53, but the slipped portion is detected as a waveform disturbance (waveform disturbance portions 59a and 59b).

In the belt slip measuring device of the fourth embodiment, the characteristic amount in the time-reflected light amount data (see FIG. 5-2) acquired by the optical sensor 54 is calculated by the analyzing device, and this is tabulated in advance. The slip amount is obtained from the correction coefficient.
An example of the feature amount will be described with reference to the graph of FIG. The pattern width 61 is a pattern size when waveform data is cut by a threshold 62 that can be arbitrarily specified, and the pattern area 63 is a pattern area when waveform data is cut by the threshold 62. The pattern width 61 is easily converted as a slip amount based on the difference from the reference pattern width as it is, but the value may vary greatly depending on the specified value of the threshold 62. The pattern area 63 cannot be directly converted into a slip amount, but stable slip detection can be expected.

Next, the correction coefficient table based on the pattern area will be described with reference to the table graph of FIG. In the figure, the horizontal axis represents the calculated pattern area, and the vertical axis represents the slip amount. The pattern area in a non-slip state is set as a standard value 65. In the case of this standard value 65, the slip amount is naturally zero. Further, when the variation of the pattern area is below a certain level, the table graph has a flat portion 66 in order to determine that the slip has not occurred. Using this table graph, the pattern area data is converted into a slip amount.
The table graph can be created by measuring the pattern on the belt and correlating it with the actual slip amount, or by detecting the slip amount simultaneously with the imaging device (CCD camera) in addition to the reflected light amount sensor. A method of detecting and correlating can be used.

FIG. 3 is a schematic diagram of an image forming / transferring mechanism unit in a conventional four-tandem full-color image forming apparatus. These are the schematic diagrams of the belt slip measuring apparatus in Example 1 of this invention. These are the pattern images in the belt slip measuring apparatus of Example 1, (a) is the pattern image before roller passing, (b) is the pattern image after roller passing. These are the belt slip measurement data by the belt slip measurement apparatus of Example 1. FIG. These are the line pattern images in the belt slip measuring apparatus of Example 1. FIG. These are the dot pattern images of the diagonal direction in the belt slip measuring apparatus of Example 1. FIG. These are the diagonal line pattern images in the belt slip measuring apparatus of Example 1. FIG. These are the schematic diagrams of the belt slip measuring apparatus in Example 2 of this invention. These are the schematic diagrams of the belt slip measuring apparatus in Example 3 of this invention. These are the pattern images in the belt slip measuring apparatus of Example 3. FIG. These are the schematic diagrams of the optical sensor in the belt slip measuring apparatus of Example 4 of this invention. These are measurement data acquired by the optical sensor in the belt slip measurement apparatus of Example 4. These are measurement data acquired by the optical sensor in the belt slip measurement apparatus of Example 4. These are the conversion table graphs in the belt slip measuring apparatus of Example 4. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming / transfer mechanism part of full color image forming apparatus 11a-11d ... Photoconductor 12 ... Intermediate transfer belt 13a-13d ... 1st transfer part 14 ... Drive roller 15a, 15b ... Driven roller 16 ... 2nd transfer section 17 ... Paper 20, 30, 40 ... Belt slip measuring device 21, 31, 41, 51 ... Belt (measurement target)
22, 32, 42 ... Roller 23, 33, 43, 53 ... Pattern 24, 34 ... Optical sensor 25, 46 ... Analysis device 27 ... Dot 28 ... Slip generation part 29 ... Pattern bulge part 35 ... ... Inkjet head 44 ... Photographing device before passing through rollers (first imaging device)
45 .. Photographic device after passing through roller (second photonic device)
48 ... Reference marker 51a ... Measuring surface 54 ... Optical sensor 55 ... Light emitting part 56 ... Light receiving part 57 ... Pattern size 58 ... Pattern pitch 59a, 59b ... Waveform disturbance part 61 ... Pattern width 62 ... Threshold 63 Pattern area 65 Standard value 66 Flat area

Claims (10)

In a belt slip measuring device for measuring a slip driven between a belt driven by a driving roller and a driven roller and the roller,
A pattern formed of a material that is not fixed to the belt on the surface of the belt that contacts the roller;
An optical sensor that measures the shape of the pattern on the belt that has passed through the roller in a driving state;
An analysis device for analyzing the measurement value of the optical sensor;
A belt slip measuring device comprising:   2. The belt slip measuring apparatus according to claim 1, further comprising an inkjet printing means for forming a pattern on the belt, wherein the pattern is formed simultaneously with driving of the belt.   The belt slip measuring device according to claim 1 or 2, wherein the pattern formed on the belt is a line pattern parallel to the axial direction of the roller.   The belt slip measuring device according to claim 1 or 2, wherein the pattern formed on the belt is a dot row oblique to the feeding direction of the belt.   The belt slip measuring device according to claim 1 or 2, wherein the pattern formed on the belt is a line pattern oblique to the feeding direction of the belt. In a belt slip measuring device for measuring a slip driven between a belt driven by a driving roller and a driven roller and the roller,
A pattern formed of a material that is not fixed to the belt on the surface of the belt that contacts the roller;
A first imaging device for imaging the pattern on the belt before it passes the roller;
A second photographing device for photographing the pattern after the pattern on the belt passes the roller;
An analysis device for analyzing pattern images acquired by the first and second imaging devices;
A belt slip measuring device comprising: The analysis device is
A function of calculating a pattern size from a pattern image acquired by the first imaging device;
A function of calculating a pattern size from a pattern image acquired by the second imaging device;
A function for calculating the difference between the two pattern sizes in time series,
The belt slip measuring device according to claim 6, wherein   The reference marker serving as a relative position reference between the pattern image acquired by the first imaging device and the pattern image acquired by the second imaging device is formed on the belt. The belt slip measuring device according to 7. In a belt slip measuring device for measuring a slip driven between a belt driven by a driving roller and a driven roller and the roller,
A pattern formed of a material that is not fixed to the belt on the surface of the belt that contacts the roller;
An optical sensor that detects the amount of reflected light from a minute region of the pattern on the belt that has passed through the roller in a driving state;
An analysis device for analyzing a change in reflected light amount in time series detected by the optical sensor;
A belt slip measuring device comprising:   10. The analysis device according to claim 9, wherein the analysis device includes a correction table for calculating a belt slip amount corresponding to a change in the amount of reflected light, and calculates the belt slip amount using the correction table. Belt slip measuring device.