PORTABLE DEVICE FOR THE CONTACTLESS MEASUREMENT OF OBJECTS

Abstract

Portable device for contactless measurement of a size, such as the diameter, of small and medium sized objects, such as wires, bars or tubes, even in movement, which comprises a light beam generator (1), two light beam deflector elements (2, 4) located opposite each other, a measuring region (3), an enlarging lens (5), a light beam splitting device (6). The light beam is split into two parts to form two separate images of the object (14) to be measured, being perceived by two linear image sensors (7.1, 7.2) and processed by two electronic circuits (8.1 and 8.2) and by an electronic processing component (9).

Claims

1. A portable device for contactless measurement of a size, such as the diameter, of small and medium sized elongated objects, such as wires, bars or tubes, even in movement, comprising: a light beam generator; a first light beam deflector element disposed frontally with respect to the light beam generator, a measuring region disposed in the path of the beam deflected by the first light beam deflector element (2), and a second light beam deflector element, disposed in an opposite position with respect to the first deflector element, in order to deflect the light beam received from the first light deflector element in an opposite direction to that in which it is emitted by the generator; an enlarging lens configured to receive the light beam from the second light beam deflector element and to create a real image of the object; a light beam splitting device located in proximity to one end of the lens configured to split the light beam of the real image into two parts, each part forming a respective image of the object to be measured; wherein it also comprises two linear image sensors provided with sensitive elements (pixels) disposed linearly; wherein the directions of alignment of the sensitive elements on the respective image planes define respective axes different from each other; and wherein the measurement of the quantity of light occurs along said axes, each of said image sensors being positioned in correspondence to the formation plane of the image of one of the two parts of the light beam split by the light beam splitter and configured to detect the quantity of light on different points of its surface and to convert it into electrical quantities; a first electronic image acquisition circuit connected to the first linear image sensor and a second electronic image acquisition circuit connected to the second linear image sensor; each electronic image acquisition circuit being configured to detect the electric charge accumulated in the different points of the corresponding linear image sensors and to convert it into a sequence of numerical values; electronic image processing components configured to determine values corresponding to respective lengths of the darkened regions, along said axes, on the two sensors and values corresponding to the central positions of the darkened regions on the positioning axes of said sensors, furthermore said electronic image processing components being configured to determine the actual value of the diameter of the object from the values corresponding to the lengths and to the central positions of the darkened regions.

2. The portable measuring device as in claim 1, wherein it comprises a support body for at least part of the components of the measuring device and a casing that encloses the support body, said casing defining at least a handle part for said device.

3. The portable measuring device as in claim 2, wherein it comprises a support element, wherein on one surface said casing has guide grooves for coupling to mating guide edges present on said support element configured to fixedly support said measuring device.

4. The portable measuring device as in claim 3, wherein said support element comprises a fixed part able to be anchored to a fixed part of a wall or a part of a machine, and a mobile part having a first inactive position substantially parallel to said fixed part and a second operating position substantially orthogonal to said fixed part, and suitable to receive said measuring device.

5. The portable measuring device as in claim 4, wherein said mobile part has a flat wall provided with attachment elements for clamping an RFID tag for the simultaneous identification of the production line.

6. The portable measuring device as in claim 2, wherein it comprises a user interface to display and set commands, provided coupled with said casing.

7. The portable measuring device as in claim 6, wherein the user interface is configured to display visible visual signals highlighting the preferential direction of the object to be measured into the measuring region.

8. The portable measuring device as in claim 1, wherein said light beam generator is formed by a LED, an aspheric lens, and a chamber which contains the aspheric lens, wherein said LED is located at a first end of the chamber and is collimated to the focus of the aspheric lens.

9. The portable measuring device as in claim 1, wherein each light beam deflector element consists of a prism equipped with a mirror on one of its oblique faces.

10. The portable measuring device as in claim 1, wherein the geometric center of the measuring region, or measurement center, is located at an intersection point O of a three axes system X, Y and Z, orthogonal with respect to each other, wherein: axis Z is parallel to the direction of propagation of the light beam which passes through the measuring region (3); axis X, orthogonal to Z, indicates the preferential alignment of the axis W of the cylindrical object (14) to be measured; axis Y, orthogonal to X and Z, indicates the preferred direction in which the diameter of the object is measured.

11. The portable measuring device as in claim 1, wherein the lens is the telecentric type; on the image plane of the lens the two axes X and Y are naturally defined, corresponding to the images of said two axes X and Y; on said image plane of the lens the image formed of the elongated object to be measured has the form of a dark band with parallel sides having a width QD inclined by an angle with respect to the axis X where Q is the enlargement of the lens and D is the diameter of the object to be measured.

12. The portable measuring device as in claim 1, wherein the light beam splitting device consists of a cube beam splitter with a 50% semi-reflecting diagonal.

13. The portable measuring device as in claim 1, wherein it comprises at least one protection element at least for said optical deflector elements, able to be selectively coupled and centered on said casing.

14. The portable measuring device as in claim 1, wherein it comprises at least one protection element at least for the hands of the operator, able to be selectively coupled and centered on said casing.

15. The method for the contactless measurement of a size, such as a diameter, of small and medium sized elongated objects, such as wires, bars or tubes, even in movement, using a portable device as in claim 1, wherein it provides that: a light beam emitted by a generator is deflected in a first direction to pass through a measuring region where the object to be measured is located or transits, and is then deflected in a second direction; the resulting beam is made to pass through a lens to create a real image of the object to be measured, after having passed through the lens, the light beam is split into two parts by a light beam splitting device; each of the two parts of the beam forms, on each linear image sensor, an image of the object to be measured in a separate spatial region from that of every other image, measurements of the quantity of light of each image occurring with a respective linear image sensor and along respective axes different from each other, in order to obtain, for each linear sensor a sequence of values on the basis of the distribution of the incident energy and representing the dark band given by the object; said sequence of values is transmitted to a corresponding electronic image acquisition circuit to determine the values corresponding to the lengths of the darkened regions on the two sensors and the values corresponding to the central positions of the darkened regions on the positioning axes of said sensors; from these values an electronic processing component determines the actual value of the diameter of the object, rendering irrelevant the orientation assumed by the object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] These and other characteristics and advantages of the present invention will become apparent from the following description of one form of embodiment, preferred but not exclusive, of the measuring device according to the present invention, given as a non-restrictive example in the attached drawings, wherein:

[0044] FIG. 1 shows a longitudinal section of the device according to the invention;

[0045] FIG. 2 shows an enlargement of the measuring region of the device in FIG. 1;

[0046] FIG. 3 shows an upper view of the measuring region;

[0047] FIG. 4 shows a front view of the measuring region;

[0048] FIG. 5 shows one of the two images of the object to be measured formed on a linear image sensor and the geometric relation between the quantity d.sub.1 detected by it and the diameter D to be measured,

[0049] FIG. 6 shows the second of the two images of the object to be measured formed on a second linear image sensor and the geometric relation between the quantity d.sub.2 detected by it and the diameter D to be measured,

[0050] FIG. 7 shows a partly exploded view of a variant of the measuring device according to the invention separated from the devices that protect the optics and the user;

[0051] FIG. 8 shows the variant in FIG. 7 in its assembled condition;

[0052] FIG. 9 shows another variant of the measuring device according to the invention, in which a support element is provided, while FIG. 10 shows the variant in FIG. 9 with the measuring device coupled with its support element.

[0053] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one form of embodiment can conveniently be incorporated into other forms of embodiment without further clarifications.

DETAILED DESCRIPTION OF ONE FORM OF EMBODIMENT

[0054] With reference to the attached drawings, the measuring device, or micrometer, according to the present invention is indicated in its entirety by the reference number 20.

[0055] With particular reference to FIG. 1, the measuring device 20 comprises a light beam generator 1, a first light beam deflector element 2 disposed frontally with respect to the light beam generator 1, a measuring region 3 disposed in the path of the deflected beam of the first deflector element 2, and a second light beam deflector element 4 disposed in an opposite position with respect to the first deflector element 2, to deflect the light beam in a direction contrary to the direction in which it is emitted by the generator 1.

[0056] The measuring device 20 also comprises, in the form of embodiment shown, a lens 5, a light beam splitting device 6, two linear image sensors 7.1, 7.2, two electronic image acquisition circuits 8.1, 8.2, and an electronic image processing component 9, a user interface 10 and an electric accumulator 11 to power the apparatus electrically and an antenna 13.6 to read an RFID tag 26, as explained in detail hereafter.

[0057] All the components cited above, except the user interface 10, are mounted on two sides of a support body 12 and are protected externally by a casing 13, which forms a handle 13.1 to hold and use the measuring device 20.

[0058] With reference to the form of embodiment in FIGS. 7 and 8, the two light beam deflector elements 2 and 4 are protected by a respective containing structure 15. Each containing structure 15, in this case, is equipped at the front with magnetic retention elements 16 and with centering elements 17 of the sphere type. The magnetic retention elements 16 and centering elements 17 allow the selective positioning of protection elements 19, shown disassembled in FIG. 7 and assembled in FIG. 8, to protect the light beam deflector elements 2 and 4.

[0059] Again with reference to FIGS. 7 and 8, it can be seen how one form of embodiment of the invention provides a protection element 18 which can be selectively assembled on the handle 13.1 to mainly protect the user's hand when measuring objects in movement at high speed and/or at high temperature.

[0060] In particular, the upper end of the protection element 18 can be removably anchored, for example by means of a screw-type attachment mean, to the containing structure 15 that protects the optical deflector 4, while the lower end of the protection element 18 can be anchored, by means of a screw-type attachment mean, to the attachment hole located on the end part of the handle 13.1.

[0061] Returning to FIG. 1, the light beam generator 1 is formed by a LED 1.1, an aspheric lens 1.2 and a chamber 1.3 that, in the case shown, contains the aspheric lens 1.2. The LED 1.1 is located at a first end of the chamber 1.3 and is collimated to the focus of the aspheric lens 1.2.

[0062] The first light beam deflector element 2 consists in this case of a 45 prism equipped with a mirror on the oblique face, and with a first side, vertical in the drawing, that closes the chamber 1.3.

[0063] The light beam generator 1 and the first light beam deflector element 2 are attached on one side of the support body 12.

[0064] The measuring region 3 is located at the front of the measuring device 20 and consists of an empty space delimited by the front wall 12.1 of the support body 12, by the second side, horizontal in the drawing, of the first light beam deflector element 2 and by a first side, also horizontal in the drawing, of the second light beam deflector element 4. The wall and sides are orthogonal with respect to each other and delimit three sides of a hollow parallelepiped.

[0065] The second light beam deflector element 4 and the remaining devices are attached on the other side of the support body 12.

[0066] The second light beam deflector element 4 is a 45 prism equipped with a mirror on the oblique face.

[0067] The second side of the second light beam deflector element 4 in this case occupies a first end of the lens 5. The lens 5 can be, for example, the telecentric type.

[0068] In proximity to the second end of the lens 5 the light beam splitter device 6 is located, consisting, for example, of a cube beam splitter with a 50% semi-reflecting diagonal.

[0069] Each of the two linear image sensors 7.1, 7.2 is positioned in correspondence to the plane struck by a part of the split light beam. The two linear image sensors 7.1, 7.2 used in the present example, although not restrictive, are two CCD or CMOS linear sensors.

[0070] A first electronic image acquisition circuit 8.1 is connected to the first linear image sensor 7.1 and a second electronic image acquisition circuit 8.2 is connected to the second linear image sensor 7.2.

[0071] The electronic image processing component 9 consists of a microprocessor unit with a memory and suitable entrance/exit ports connected to the electronic image acquisition circuits 8.1, 8.2 and with the user interface 10.

[0072] In an advantageous form of embodiment, the user interface 10 comprises an LCD graphic screen, a series of buttons, and an acoustic alarm; there can advantageously be a LED light to indicate the condition of the battery. The handle 13.1 also has a button 13.2, a safety button 13.4 and a USB port, as an example of a peripheral connection device 13.5, as well as the antenna 13.6 for reading an RFID tag 26, shown hereafter.

[0073] During use, in order to measure an elongated object 14 to be measured, the light generated by the LED 1.1, after having passed through the aspheric lens 1.2, has the form of an extended and collimated light beam that reaches the second end of the chamber 1.3. The light beam has a roughly uniform distribution of radiant energy, both spatially on an area perpendicular to the axis of the beam and also angularly for directions comprised within a certain angle from the axis.

[0074] The first light beam deflector element 2 conditions the light beam emitted by the light beam generator 1 so that it passes through the measuring region 3 in a direction substantially orthogonal with respect to the direction prescribed for the axis W of the object 14 to be measured and that completely illuminates the whole extension of the measuring region 3 so that the measuring can be done in all the permitted positions of the object 14.

[0075] In the measuring region 3 three axes Z, X, Y are defined which are orthogonal with respect to each other, intersecting said measuring center at a point O. Axis Z is parallel to the direction imposed on the light beam by the first light beam deflector element 2. Axis X, orthogonal to axis Z, indicates the preferential alignment of the axis of the object 14 to be measured. Axis Y, orthogonal to X and Z, indicates the direction in which the diameter of the object 14 is measured. The intersection point O of the three axes X, Y, Z is located at the geometric center of the measuring region 3.

[0076] The exit side of the first light beam deflector element 2 and the entrance side of the second light beam deflector element 4 are parallel to each other, perpendicular to axis Z and parallel to axes X, Y. The wall 12.1 of the support body 12 that delimits the measuring region 3 is parallel to axis Z and axis X.

[0077] The object 14 to be measured is introduced into the measuring region 3 without either position or orientation being known.

[0078] The disposition of the first light beam deflector element 2 is such that the object 14 is lit from behind with respect to the lens 5. The image which forms on the side of the second light beam deflector element 4 that delimits the measuring region 3 has the characteristic of an outline or silhouette, dark and without other details other than an outline on a clear background.

[0079] The second light beam deflector element 4 again directs the light beam at 90 so that, after passing through the measuring region 3, the light beam is aligned and centered on the optical axis of the lens 5. The lens 5 creates a real image of the object 14 to be measured, whose shape corresponds to the orthogonal projection of the object 14 on the plane XY as defined above, enlarged by a constant factor Q characteristic of the particular lens 5 used.

[0080] The size of the image is independent of translations of the object 14 to be measured along the axis Z of the measuring region. On the image plane the two axes X.sup.1 and Y.sup.1 are naturally defined, corresponding to the images of the two axes X and Y previously defined.

[0081] The image formed on the image plane of the lens 5 is a dark band with parallel edges that form an angle with respect to the axis X.sup.1 and a width equal to Q times the diameter D of the object 14 to be measured.

[0082] The light beam, after having passed through the lens 5, is split into two parts by the light beam splitter 6, each of which forms on each linear image sensor 7.1, 7.2 an image of the object 14 to be measured that is geometrically equal to the one that would have been formed directly by the lens 5 but in a separate spatial region from those of each other image. In this way the two linear image sensors 7.1, 7.2, located in correspondence to the two parts of the separate images that correspond either completely or partly to the same region of the original image, can be simultaneously activated without the two linear image sensors 7.1, 7.2 interfering mechanically with each other.

[0083] The position of each linear image sensor 7.sub..Math.k (where 7.sub..Math.k indicates the first sensor 7.1 or the second sensor 7.2) with regard to its own image plane is individually identified by three coordinates x.sub.0k, y.sub.0k and .sub.k that describe the position of the central point of the linear image sensor 7.sub..Math.k in a system of axes X.sub.k, Y.sub.k and the angle formed by axis s.sub.k of the linear image sensor 7.sub..Math.k with axis Y.sub.k of the image plane.

[0084] Each linear image sensor 7.1, 7.2 supplies the distribution of light energy incident on the image along a rectilinear segment of the image itself.

[0085] The linear image sensors 7.1, 7.2 located on the planes of the two images produced by the light beam splitter device 6 are positioned so as to affect distinct segments. The segment of image corresponding to each sensor 7.sub..Math.k can then be identified by the coordinates x.sub.0k, y.sub.0k that the central point of the sensor occupies in the image plane and by the angle .sub.k formed by the axis s.sub.k of each linear image sensor 7.sub..Math.k with the axis Y.sub.k (image of axis Y) of the associated image plane.

[0086] In this preferential form of embodiment, the central point of the linear image sensors 7.1, 7.2 is given by the coordinates

x.sub.01,y.sub.01=0

x.sub.02,y.sub.02=0

and for each linear image sensor 7.1, 7.2 the angle is given by

.sub.1=+7.5, .sub.2=7.5

[0087] The individual points of the segment identified by the linear image sensors 7.1, 7.2 are described by a coordinate s.sub.k directed along the segment and originating in the point where the segment intersects axis Y.sup.1.

[0088] When the object 14 to be measured is positioned correctly in the measuring region 3, each sequence of values produced by each sensor and representing the distribution of light energy incident on it is formed by a region of high values of the incident energy followed by a region of low values, corresponding to the passage of the dark band formed on the image by the object 14 and followed by another region of high values. The region of low values is determined for each sensor 7.sub..Math.k by two quantities d.sub.k and c.sub.k that respectively represent the length of the segment on the sensor 7.sub..Math.k obscured by the image of the object 14 to be measured (the black strip in FIGS. 5 and 6) and the position on the axis s.sub.k of the center of the same segment.

[0089] Each electronic image acquisition circuit 8.1, 8.2 obtains information relating to the distribution of light energy from each of the two linear image sensors 7.1, 7.2 and transmits the digitalized values of the measurements to the electronic image processing component 9. The electronic image processing component 9 provides to control and receive the two sequences of numerical values from the two electronic acquisition circuits 8.1, 8.2 and determines the values d.sub.1 and d.sub.2 corresponding to the lengths of the obscured regions on the two sensors and the values c.sub.1 and c.sub.2 corresponding to the central positions of the regions obscured on axes s.sub.1 and s.sub.2.

[0090] The value of the angle can then be calculated by the formula:

[00001]$\mathrm{tg}\left(-\frac{{}_1+{}_2}{2}\right)=\frac{1}{\mathrm{tg}\left(\frac{{}_1+{}_2}{2}\right)}.Math.\frac{d_1-d_2}{d_1+d_2}$

[0091] The calculation program performed by the electronic image processing component 9 comprises an algorithm that uses this formula to determine the value of . When this is known, the calculation program can be continued to determine the diameter D of the object 14 in the form:

[00002]$D=\frac{1}{2.Math.Q}.Math.\left(d_1.Math.\cos \left({}_1+\right)+d_2.Math.\cos \left({}_2+\right)\right)$

[0092] In another preferential form of embodiment the two linear image sensors 7.1, 7.2 are positioned so that .sub.1 is equal to .sub.2. In this case the value of the angle can be calculated by the formula:

[00003]$\mathrm{tg}.Math..Math.=\frac{y_{02}-y_{01}+\left(c_2-c_1\right).Math.\cos .Math..Math.{}_1}{x_{02}-x_{01}+\left(c_2-c_1\right).Math.\mathrm{sen}.Math..Math.{}_1}$

Once is known, the calculation program can be continued to determine again the diameter D of the object 14 in the form:

[00004]$D=\frac{1}{2.Math.Q}.Math.\left(d_1.Math.\cos \left({}_1+\right)+d_2.Math.\cos \left({}_2+\right)\right)$

[0093] When each acquisition and calculation procedure is completed, the electronic processing component 9 sends to the user interface 10 the numerical value of the measurement of the diameter D of the object 14 indicating the unit of measurement selected or a possible error condition that are displayed on the LCD graphic screen.

[0094] The buttons of the user interface 10 command at least the activation/de-activation of the apparatus, the start of the acquisition and calculation procedure, the activation/de-activation of the continuous display of the orientation of the object 14 to be measured, the change of the unit of measurement and the illumination function of the LCD screen. A button 13.2 to activate/de-activate the apparatus is positioned on the handle 13.1.

[0095] If activated by a button, an image is displayed on the LCD screen of the user interface 10. The image describes graphically the deflection of the axis of the object 14 with respect to the ideal orientation, showing two segments that intersect with an angle proportionate to the deflection. This allows to verify the quality of the alignment of the object 14 with respect to the axis X in the measuring region 3, and to make the necessary movement of the hand to correctly obtain the measuring operation. The user is assisted in this operation by acoustic signals and by sight lines or colored areas present on the casing 13. Furthermore, as each acquisition and calculation procedure is completed, the numerical value of the measurement D is displayed, indicating the unit of measurement selected or a possible error condition. The user interface 10 also allows to view interesting statistics of repeated measurements and data on the devices of the apparatus in order to configure it in the best possible way. In one form of embodiment of the present invention, shown in FIGS. 9 and 10, a support element 21 is provided, which allows to position the measuring device 20 fixedly along the production line, for example attaching it to a machine where the objected 14 subjected to measuring is worked.

[0096] The support element 21 comprises a fixed part 22 and a mobile part 23. The fixed part 22 comprises seatings 24 to attach it to a wall of the machine or other fixed part, for example a wall 28.

[0097] The mobile part 23 can rotate in direction A from a vertical position, substantially parallel to the fixed part 22 when not in use, to a substantially horizontal position, shown in FIGS. 9 and 10, where the measuring device 20 can be coupled with the support element 21.

[0098] The mobile part 23 comprises a flat upper wall 27; the support element 21 comprises, at the lower part and at the sides of the flat wall 27, two edges parallel to the flat wall 27 which cooperate with mating grooves 13.3 present in the upper part of the casing, promoting the insertion through sliding of the measuring device 20 on the support element 21, until it is clamped. Using the support element 21 allows to position the measuring device 20 easily and quickly, guaranteeing the plan positioning and centering thereof with respect to the object 14 to be measured.

[0099] Furthermore, using a plurality of support elements 21 distributed on several lines or at several predetermined points of the same line allows to periodically monitor several production lines using a single measuring device 20, possibly after simultaneous identification of said line or specific segment of line using an identification device, such as a tag, bar code or other similar element.

[0100] In one form of embodiment, the identification device can be an RFID tag 26 attached on the lower side of the flat wall 27 by attachment elements 25, for example screws or rivets or suchlike, possibly using support elements, not shown. In particular, when the apparatus is attached to the support element 21, the RFID tag 26 identifies the production line in correspondence with which it is detecting the data, through the antenna 13.6 mentioned above, and also its position along the line, any possible work under way and other possible information that can be useful during measuring.

[0101] Modifications and variants may be made to the present invention, all of which shall come within the field of protection defined by the attached claims.