JP2009288134A - Medium thickness measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a thickness of a medium with high accuracy. <P>SOLUTION: A medium thickness measuring apparatus 10 includes a reference roller 100, a first measuring section 200A which acquires a first measured value combining the thickness of the medium and a thickness measurement error due to an error factor of the reference roller, a second measuring section 200B which is positioned shifted from the first measuring section by a predetermined phase difference θ and acquires as a second measured value the thickness measurement error due to the error factor of the reference roller in a phase measured by the first measuring section, and a medium thickness acquiring section 350 which shifts the second measured value by the second measuring section by the phase difference and obtains a difference from the first measured value by the first measuring section to acquire the thickness of the medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for measuring the thickness of a medium.

  Various devices for improving the accuracy of an apparatus for measuring the thickness of a medium have been made. For example, a method is known in which a second probe is provided at a position symmetrical to the first probe with respect to the center of the reference roller (Patent Document 1). In this method, the displacement amount obtained by adding the thickness of the medium and the displacement amount of the reference roller is taken in from the change amount of the first probe, and the displacement amount of the reference roller is taken in from the change amount of the second measurer. The error caused by the eccentricity of the center of rotation of the reference roller from the center of the reference roller is corrected using two displacement amounts.

JP-A-5-141957

  However, in the conventional method, it is difficult to correct an error caused by the circularity of the reference roller and an error caused by unevenness on the surface of the reference roller.

  An object of the present invention is to solve at least one of the above problems and to measure the thickness of a medium with high accuracy.

  In order to solve at least a part of the above problems, the present invention takes the following aspects.

  According to a first aspect of the present invention, there is provided a medium thickness measuring apparatus that obtains a first measurement value obtained by combining a reference roller, a thickness of the medium, and a thickness measurement error due to an error factor of the reference roller. A thickness measurement error due to an error factor of the reference roller in the phase measured by the first measurement unit is arranged at a position shifted by a predetermined phase difference from the measurement unit and the first measurement unit. The second measurement unit acquired as a value and the second measurement value obtained by the second measurement unit are shifted by the phase difference, and the difference between the first measurement value obtained by the first measurement unit is obtained, A medium thickness acquisition unit that acquires the thickness of the medium. According to this aspect, the reference roller in the phase in which the first measurement unit measures the value of the error of the reference roller and the thickness of the medium, and the second measurement unit measures the thickness of the medium by the first measurement unit. Therefore, the thickness of the medium can be obtained with high accuracy from the difference.

  1st aspect of this invention WHEREIN: The said 1st and 2nd measurement part is equipped with the detection roller which contact | connects the said reference roller, The diameter of the said reference roller may be an integral multiple of the diameter of the said detection roller. . According to this aspect, since the point on the detection roller that contacts an arbitrary point on the reference roller is the same, the error can be reduced.

  In the first aspect of the present invention, the first detection roller of the first measurement unit and the second detection roller of the second measurement unit may have the same diameter. According to this aspect, since the point on the first detection roller and the point on the second detection roller that are in contact with an arbitrary point on the reference roller are the same, the error can be reduced.

  In the first aspect of the present invention, the first measurement unit performs measurement at a timing when a specific point on the first detection roller contacts the reference roller, and the second measurement unit performs the second detection. The measurement may be performed at a timing when a specific point on the roller contacts the reference roller. According to this aspect, since the same point on the detection roller is in contact with the reference roller at the time of measurement, an error of the detection roller can be removed.

  In the first aspect of the present invention, the medium thickness acquisition unit calculates the difference between the maximum value and the minimum value among the measurement value changes by the first measurement unit when the medium is not measured. You may provide the correction | amendment part which correct | amends at least one of the said 1st measurement part and a 2nd measurement part so that it may become equal to the difference of the maximum value of measurement value changes by a measurement part, and a minimum value. According to this aspect, it is possible to suppress an error due to a difference in sensitivity between the first measurement unit and the second measurement unit.

  In the first aspect of the present invention, the correction unit may set the average value to zero for the measurement value obtained by the first measurement unit and the measurement value obtained by the second measurement unit when the medium is not measured. . According to this aspect, the zero point correction of the first measurement unit and the second measurement unit can be performed.

  In the first aspect of the present invention, the phase difference acquisition further acquires the phase difference between the first measurement unit and the second measurement unit using the first measurement value and the second measurement value. May be provided. According to this aspect, the phase difference between the first measurement unit and the second measurement unit can be obtained without strictly arranging the first measurement unit and the second measurement unit. The thickness can be determined with high accuracy.

  The first aspect of the present invention further includes a medium transport unit that sends the medium to the second measurement unit, and the phase difference acquisition unit has a first measurement value by the first measurement unit determined in advance. Between the first measurement unit and the second measurement unit, based on the difference between the timing at which the second measurement value has shifted more than a predetermined value and the timing at which the second measurement value by the second measurement unit has shifted more than a predetermined value. A phase difference may be acquired. When measuring the medium, the measured value varies more than the error of the reference roller depending on the presence or absence of the medium. Therefore, it is possible to acquire the timing at which such fluctuations occurred in the first measurement unit and the second measurement unit, respectively, and to acquire the phase difference between the first measurement unit and the second measurement unit from the difference. Is possible.

  The present invention can be realized in various forms, for example, in various forms such as a medium thickness measuring apparatus, a medium thickness measuring method, and a medium thickness measuring accuracy improving method. be able to.

First embodiment:
FIG. 1 is a schematic configuration diagram of a medium thickness measuring apparatus according to the first embodiment. The medium thickness measuring apparatus 10 includes a reference roller 100 and two measuring units 200A and 200B. Since the two measuring units 200A and 200B have the same configuration, “A” and “B” are omitted and referred to as “measuring unit 200” when they are not distinguished from each other. The reference roller 100 is driven and rotated by a motor (not shown) to convey the medium 400. The first measurement unit 200A includes a detection roller 210A, a detection lever 220A, a linear output sensor 230A, and a spring 240A. The same applies to the second measuring unit 200B. The detection roller 210 is in contact with the reference roller 100 and rotates as the reference roller 100 rotates. The size of the angle ∠AOB formed by the contact position A between the first detection roller 210A and the reference roller 100, the rotation center O of the reference roller 100, and the contact position B between the second detection roller 210B and the reference roller is θ. In the present embodiment, this θ is also referred to as “phase difference” between the first measurement unit 200A and the second measurement unit 200B. The phase difference is generally known because it is determined by the mounting positions of the measurement units 200A and 200B. When the reference roller 100 rotates, it is detected according to error factors including distortion of the reference roller 100 from a perfect circle, eccentricity that is a deviation between the center of the reference roller 100 and the rotation center, and unevenness of the reference roller 100. The roller 210 moves up and down in the radial direction of the reference roller 100. The first detection roller 210 </ b> A moves up and down in the radial direction of the reference roller 100 according to the thickness of the medium 400 when the medium 400 passes between the first detection roller 210 </ b> A and the reference roller 100. That is, the vertical movement of the first detection roller 210A is a combination of the vertical movement due to the error factor and the vertical movement due to the thickness of the medium.

  The thickness detection lever 220 supports the detection roller 210 and transmits a change in the position of the detection roller 210 to the linear output sensor 230. The linear output sensor 230 acquires the amount of change of the detection roller 210. For example, it is possible to detect the amount of displacement of the detection roller 210 by arranging the linear output sensor 230 at the fulcrum of the thickness detection lever 220 and detecting the fulcrum angle of the thickness detection lever 220. The first linear output sensor 230A and the second linear output sensor 230B are corrected so that the difference between the maximum value and the minimum value of the measured value of the reference roller 100 when the medium is not measured is the same. . Thereby, it is possible to correct the difference in sensitivity between the first linear output sensor 230A and the second linear output sensor 230B. Further, the linear output sensors 230A and 230B are zero-point corrected so that the average value of measured values when the reference roller 100 rotates without the medium 400 becomes zero. The spring 240 is an elastic body for applying an elastic force so that the detection roller 210 is in pressure contact with the reference roller 100.

FIG. 2 is an explanatory diagram showing the outputs of the linear output sensors 230A and 230B when the reference roller is rotated without inserting the medium 400. FIG. Normally, the output value of the linear output sensor 230 (hereinafter also referred to as “displacement amount”) is a certain value if there are no error factors (deviation from a perfect circle, eccentricity, surface irregularities) caused by the reference roller 100. Become. Note that if the measured values of the linear output sensors 230A and 230B are zero-point corrected, this constant value is zero. However, when there are these error factors, an error appears in the output value of the linear output sensor 230 with a period of one rotation of the reference roller 100. For example, when the reference roller 100 has irregularities and the contact point with the first detection roller 210A changes from a convex portion to a concave portion, a Pa portion whose value greatly decreases appears in the output of the first linear output sensor 230A. The Pa portion appears again after one cycle. Further, Pa section, as also Pa 'section at the output of the second linear output sensor 230B, appearing after t _theta from the occurrence of the Pa unit. Here, if the angular velocity of rotation of the reference roller 100 is ω, the phase difference θ between the first measurement unit 200A and the second measurement unit 200B is
θ = t _θ・ ω
There is a relationship.

  FIG. 3 is an explanatory diagram showing a measurement value processing unit of the medium thickness measuring apparatus 10. The medium thickness measurement apparatus 10 includes an amplifier 310, an A / D converter 320, a sampling clock generation unit 330, a storage unit 340, and a CPU 350 as a measurement value processing unit 300. The output of the linear output sensor 230 is amplified by the amplifier 310 and converted from analog data to digital data by the A / D converter 320. This digital data is stored in the storage unit 340 for each clock from the sampling clock generation unit 330. The CPU 350 functions as a medium thickness acquisition unit that acquires the thickness of the medium using digital data in the storage unit 340, and also functions as a correction unit that performs sensitivity correction and zero point correction of the linear output sensor 230 described above. .

FIG. 4 is an explanatory diagram schematically showing the principle of canceling the error. In FIG. 4A, the output value from the first linear output sensor 230A is plotted above the output value from the second linear output sensor 230B for convenience of illustration. As shown in FIG. 4 (b), CPU 350 shifts the measurement data t _theta minutes ahead from the second linear output sensor 230B. Next, as shown in FIG. 4C, the CPU 350 takes a difference between the measurement data from the first linear output sensor 230A and the measurement data from the shifted second linear output sensor 230B. As shown in FIG. 4C, the difference is zero at any point in time and does not change with time. That is, the error is offset.

This principle can be considered as follows. That is, error factors of the error generated in the first measurement unit 200A at some point (located on the reference roller 100 phase) is applied to the measurement by the second measurement unit 200B after t _theta. The error due to this error factor is also measured in the second measuring unit 200B. At this time, the error generated in the first measurement unit 200A and the error generated in the second measurement unit 200B are the same because the error factors are the same. Thus, (a phase difference theta min) measured data t _theta fraction from the second linear output sensor 230B is shifted forward, to offset the error by taking the difference between the data from the first linear output sensor 230A It is possible. In this way, no means is required for detecting the rotational position of the reference roller 100.

  FIG. 5 is an example of the output of the linear output sensor 230 when the medium 400 is measured. As shown in FIG. 5A, the output value of the first linear output sensor 230A is a value obtained by adding the value of the thickness measurement error due to the error factor of the reference roller 100 and the thickness of the medium. On the other hand, as shown in FIG. 5B, the output value of the second linear output sensor 230B is the value of the thickness measurement error due to the error factor of the reference roller 100, and is the same as the value shown in FIG. These values are amplified by the amplifier 310 of the processing unit 300 shown in FIG. 3, A / D converted by the A / D converter 320, and then stored in the storage unit 340 along with the measurement time by the CPU 350.

  The CPU 350 reads the measurement time and the output value of the second linear output sensor 230B from the storage unit 340. Next, the CPU 350 shifts the output value by θ. Specifically, CPU 350 subtracts tθ from the read measurement time. The CPU 350 reads the measurement time and the output value of the first linear output sensor 230A from the storage unit 340. Next, the CPU 350 takes a difference between the output value of the first linear output sensor 230A and the output value of the shifted second linear output sensor 230B.

  FIG. 6 is a graph in which differences are plotted. In FIG. 6, data obtained by combining the thickness of the medium 400 and the attached material on the medium 400 is plotted, and the thickness measurement error due to the error factor of the reference roller 100 is offset by taking the difference. Note that the CPU 350 calculates a difference by using an average value or a moving average value of the displacement amounts of a plurality of measurement times as a new displacement amount in order to prevent false detections such as noise, The difference may be calculated using the integral value as a new displacement amount.

As described above, according to the present embodiment, the difference between the output value of the second linear output sensor 230B and the output value of the first linear output sensor 230A before t _θ before that is caused by an error factor. Therefore, the thickness of the medium can be measured with high accuracy. If accurate media thickness data can be obtained, it is possible to improve the determination of the presence / absence of a patch on the medium and the accuracy of determining the type of medium thickness. Note that obtains the output value of the first linear output sensor 230A, may offset the error caused by the error factor by taking the difference between the output value of the second linear output sensor 230B after t _theta.

  In the present embodiment, the sizes of the reference roller 100 and the detection roller 210 are not particularly limited, but the diameter of the reference roller 100 may be an integral multiple of the diameter of the detection roller 210. In this way, the point on the detection roller 210 where the specific point x (FIG. 1) on the reference roller 100 contacts is always the specific point y (point y ′), so that the error between the reference roller 100 and the detection roller 210 is reduced. It is possible to cancel the combined values and improve the measurement accuracy. In this case, it is preferable that the first detection roller 210A and the second detection roller 210B have the same diameter.

  In the present embodiment, the cycle of the sampling clock is not limited, but may be a cycle in which a specific point y on the detection roller 210 is in contact with the reference roller 100. In this way, the error factor due to the detection roller 210 is only the error factor at the point y, so that the error due to the detection roller 210 can be offset. For example, the radius of the reference roller 100 is R, the angular velocity is ω, and the radius of the detection roller is r. At this time, the period T of the sampling clock may be an integer multiple of T = 2πr / Rω. The detection roller 210 is preferably small. This is because the sampling clock cycle can be shortened.

  In this embodiment, the measurement unit 200 is a contact type using the detection roller 210, but may be a non-contact type using laser interference, for example. In this way, it is possible to eliminate errors caused by the detection roller 210.

  In this embodiment, when the output is shifted, the timing difference between the first linear output sensor 230A and the second linear output sensor 230B is used. However, the number of data may be used.

Second embodiment:
FIG. 7 is a schematic configuration diagram of a medium thickness measuring apparatus according to the second embodiment. The medium thickness measuring apparatus according to the second embodiment includes a conveyance switching roller 250 and a conveyance guide 260 in addition to the configuration of the medium thickness measuring apparatus according to the first embodiment. The conveyance switching roller 250 switches the conveyance destination of the medium 400 between the arrow C direction and the arrow D direction. The conveyance guide 260 guides the medium 400 during conveyance in the direction of arrow D.

  The medium thickness measuring apparatus of the second embodiment has two operations. The first operation is an operation for measuring the thickness of the medium 400. In this operation, the conveyance switching roller 250 is retracted by an actuator (not shown). The medium 400 is conveyed in the direction of arrow C and not conveyed in the direction of arrow D. The first operation is the same as that of the first embodiment. The second operation is an operation for obtaining a phase difference between the first measurement unit 200A and the second measurement unit 200B. In this operation, the conveyance switching roller 250 moves while being pressed in the direction of the reference roller 100 by an actuator (not shown). As a result, the medium 400 is conveyed in the direction of arrow D. Therefore, the medium 400 is measured by the first measurement unit 200A and the second measurement unit 200B.

  FIG. 8 is an example of outputs from the linear output sensors 230A and 230B in the second operation. The output values of the linear output sensors 230 </ b> A and 230 </ b> B are values obtained by adding an error due to the error factor of the reference roller 100 and the thickness of the medium 400. The outputs of the linear output sensors 230A and 230B are shifted in phase difference, but the output waveforms have the same shape. Therefore, the phase difference can be obtained by comparing the outputs of the linear output sensors 230A and 230B. Here, in general, the thickness of the medium 400 is larger than the error due to the error factor of the reference roller 100. Therefore, when the medium 400 is detected, the output value of the linear output sensor rises greatly. The CPU 350 can obtain the rising timings of the linear output sensors 230A and 230B, respectively, and can obtain the phase difference from the difference.

The CPU 350 processes the outputs of the linear output sensors 230 </ b> A and 230 </ b> B with the processing unit illustrated in FIG. 3 and stores the measurement timing and the output value in the storage unit 340. The CPU 350 searches for the measurement values taken into the storage unit 340, and acquires the measurement timings Ta and Tb at which the change in the measurement value is equal to or greater than a certain value for each of the outputs of the linear output sensors 230A and 230B. This constant value may be the same as the thickness of the medium 400, for example. In addition, as long as the medium 400 can be determined to have reached the measuring unit 200, the certain value may be a value smaller than the thickness of the medium, for example, half the thickness of the medium 400. Normally, the timings Ta and Tb are one for each of the outputs of the linear output sensors 230A and 230B, and correspond to the timing when the medium 400 reaches the respective measuring units 200. Therefore, the timing Ta, it is possible to obtain from the difference T _theta of Tb phase difference between the first measuring section 200A and the second measurement unit 200B.

  As described above, according to the second embodiment, for each of the outputs of the linear output sensors 230A and 230B, the measurement timings Ta and Tb at which the change in the measurement value is equal to or greater than a certain value are acquired, and the first measurement unit 200A and the first measurement unit 200A It becomes possible to obtain the phase difference of the two measurement units 200B. Although the present embodiment has been described using timing, since the timing and the phase of the reference roller 100 correspond to each other, the same applies even if the phase is used instead of the timing. Thereby, it is possible to easily correct an error in an arbitrary mounting position such as a secular change of the thickness detecting device. In addition, when the measurement unit 200 is first arranged, there is no need for exact alignment. After the measurement unit 200 is arranged, according to the procedure of the second operation, the first measurement unit and the second measurement unit are arranged. What is necessary is just to obtain | require a phase difference.

  In the second embodiment, the phase difference between the first measurement unit 200A and the second measurement unit 200B is obtained from the timing when the output of the linear output sensor 230 rises, but from the timing when the output of the linear output sensor 230 falls. You may ask for it.

  In the second embodiment, the medium 400 is measured when the phase difference is obtained. However, the phase difference can be obtained without using the medium 400. For example, the CPU 350 may obtain a measurement time at which the change in output at each measurement timing becomes the largest for each measurement unit 200A and 200B, and obtain the phase difference using the difference between the measurement times. For example, in FIG. 2, it is Ta that the output of the first linear output sensor 230A changes most greatly, and the output of the second linear output sensor 230B changes most greatly is Tb. The CPU 350 can obtain the phase difference from the difference between Ta and Tb. Note that the time when the output changes the most can be easily obtained by using the difference between the output values of the linear output sensor 230 at the adjacent measurement timings.

  The embodiments of the present invention have been described above based on some examples. However, the above-described embodiments of the present invention are for facilitating the understanding of the present invention and limit the present invention. It is not a thing. The present invention can be changed and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.

It is a schematic block diagram of the medium thickness measuring apparatus which concerns on a 1st Example. FIG. 6 is an explanatory diagram illustrating outputs of linear output sensors 230A and 230B when a reference roller is rotated without inserting a medium 400. 4 is an explanatory diagram showing a processing unit for measured values of the medium thickness measuring apparatus 10. FIG. It is explanatory drawing which shows the principle which offsets an error typically. 6 is an example of the output of the linear output sensor 230 when the medium 400 is measured. It is the graph which plotted the difference. It is a schematic block diagram of the medium thickness measuring apparatus which concerns on a 2nd Example. It is an example of the output of the linear output sensors 230A and 230B in 2nd operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Measuring apparatus 100 ... Reference | standard roller 200 ... Measuring part 210 ... Detection roller 220 ... Detection lever 230 ... Linear output sensor 240 ... Spring 250 ... Conveyance switching roller 260 ... Conveyance guide 300 ... Processing part 310 ... Amplifier 330 ... Sampling clock generation part 340 ... Storage unit 400 ... Medium

Claims (8)

A medium thickness measuring device comprising:
A reference roller;
A first measurement unit for obtaining a first measurement value obtained by combining a thickness of the medium and a thickness measurement error due to an error factor of the reference roller;
A thickness measurement error caused by an error factor of the reference roller in a phase measured by the first measurement unit, which is arranged at a position shifted by a predetermined phase difference from the first measurement unit, is obtained as a second measurement value. A second measuring unit;
The medium thickness acquisition for acquiring the thickness of the medium by shifting the phase difference of the second measurement value by the second measurement unit and obtaining the difference from the first measurement value by the first measurement unit. And
A medium thickness measuring device. The medium thickness measuring apparatus according to claim 1,
The first and second measuring units include a detection roller that contacts the reference roller,
The medium thickness measuring apparatus, wherein the diameter of the reference roller is an integral multiple of the diameter of the detection roller. The medium thickness measuring apparatus according to claim 2,
The medium thickness measurement apparatus, wherein the first detection roller of the first measurement unit and the second detection roller of the second measurement unit have the same diameter. In the medium thickness measuring apparatus according to claim 3,
The first measurement unit performs measurement at a timing when a specific point on the first detection roller contacts the reference roller,
The medium thickness measuring apparatus, wherein the second measuring unit performs measurement at a timing when a specific point on the second detection roller comes into contact with the reference roller. In the medium thickness measuring device according to any one of claims 1 to 4,
The medium thickness acquisition unit calculates the difference between the maximum value and the minimum value among the measurement value changes by the first measurement unit when the medium is not measured, among the measurement value changes by the second measurement unit. A medium thickness measurement apparatus comprising: a correction unit that corrects at least one of the first measurement unit and the second measurement unit so as to be equal to a difference between a maximum value and a minimum value. In the medium thickness measuring apparatus according to claim 5,
The said correction | amendment part is a medium thickness measuring apparatus which makes an average value zero each about the measured value by the said 1st measuring part when not measuring a medium, and a measured value by the said 2nd measuring part. The medium thickness measuring apparatus according to any one of claims 1 to 6, further comprising:
A medium thickness measurement apparatus comprising: a phase difference acquisition unit that acquires a phase difference between the first measurement unit and the second measurement unit using the first measurement value and the second measurement value. The medium thickness measuring apparatus according to claim 7, further comprising:
A medium conveying unit for sending the medium to the second measuring unit;
The phase difference acquisition unit includes a timing at which the first measurement value by the first measurement unit transitions to a predetermined value or more, and a second measurement value by the second measurement unit is a predetermined value or more. A medium thickness measurement apparatus that obtains a phase difference between the first measurement unit and the second measurement unit from a difference from a transition timing.

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