DE202019106722U1 - Device with a line sensor - Google Patents

Abstract

Device (1) with a line sensor (2) and a light source (3) and an object (4) which is partially transparent, the object (4) being arranged between the line sensor (2) and the light source (3), the Light beams from the light source (3) partially penetrate the object (4) and strike the line sensor, the line sensor (2) having a control and evaluation unit (6), characterized in that the object (4) is made of plastic, wherein the object (4) has at least two parallel plastic films (7, 8), the object (4) having a weld seam (9) in at least one area, whereby the two plastic films (7, 8) are materially connected, with the light at least is recorded in a first area (10) of the object (4) with the weld seam (9) and at least in a second area (11) of the object (4) without a weld seam (9), the control and evaluation unit (6) the the light intensity of the first B detected by the line sensor (2) area (10) and the second area (11) are compared with each other, whereby the weld seam (9) is detected by the control and evaluation unit (6) that the detected light intensity in the first area (10) is higher than in the second Area (11).

Description

The present invention relates to a device according to the preamble of claim 1.

Such devices are for example from DE102009012558A1 or the DE102014220598A1 known.

The disadvantage of the known devices is that they are not sensitive enough.

One object of the invention is to provide an improved device for object inspection which has a high sensitivity.

The object is achieved according to claim 1 by a device with a line sensor and a light source and an object which is partially transparent, the object being arranged between the line sensor and the light source, the light rays from the light source partially penetrating the object and striking the line sensor , the line sensor having a control and evaluation unit, the object being made of plastic, the object having at least two parallel plastic films, the object having a weld seam in at least one area, whereby the two plastic films are materially connected, the light at least is recorded in a first area of the object with the weld seam and at least in a second area of the object without a weld seam, the control and evaluation unit comparing the light intensity of the first area and the second area detected by the line sensor, with the weld seam as a result, it is detected by the control and evaluation unit that the detected light intensity or the transmission is higher in the first area than in the second area.

The two plastic films are bonded to one another by the weld seam. As a result, two boundary layers are connected to one another, as a result of which reflections are reduced, as a result of which transmission in the area of the weld seam is increased and the weld seam can be detected.

Since the increase in transmission in the area of the weld seam is very small, the light intensity is recorded in a second area which has no weld seam. This makes it possible to detect very small differences in brightness.

The line sensor with a large number of receiving elements in a row or row also evaluates a plurality of receiving elements in the first area and the second area, as a result of which multiple detection takes place in the first and second area, which enables more precise detection. The brightness values or light intensity values of the respective individual receiving elements in the first area and the second area can be averaged, for example, in order to obtain an average light intensity value for each area.

The detection with a line sensor allows a fast recording speed, since the line sensor can be read out quickly.

The line sensor is preferably arranged transversely to the weld seam. The optical axes of the line sensor are also arranged transversely to the weld seam.

A change in the brightness values between different measurements can preferably also be recorded, as a result of which quality fluctuations in the weld seam can be detected.

The line sensor is arranged, for example, together with the control and evaluation unit in a first housing. Furthermore, the light source is arranged in a second housing, which is arranged at a distance from the first housing. As a result, the light source can be positioned variably in relation to the line sensor.

The line sensor is an optoelectronic sensor for the optical, contactless detection of objects, in particular contrasting edges.

In a further development of the invention, the object is a packaging, the packaging being made of light-colored and white plastic film in the first and second areas. The plastic film is more translucent, which means that a weaker light source can be used. Due to the weld seam, the packaging can be easily closed in an automated process.

In a further development of the invention, the plastic film has air cushioning, the surface being a non-uniform and uneven surface. The contents of the packaging are protected by the air cushioning. However, the air cushioning also leads to further boundary layers being present which each lead to light reflections which lead to a lower transmission in the second area. In the first area of the weld seam, the air cushioning is partially destroyed by the plastic welding process, whereby the transmission is increased in the first area, as a result of which the difference in brightness differences is increased, which ensures better detection.

In the arrangement with transmitted light, there is no use of reflection in this system. Also at Excessive directional light coupling is prevented from emerging from the plastic film. The plastic film thereby forms an optical diffuser which forms diffusely scattered light. The plastic film preferably has a matt, matt or partially matt surface on the outer surface, as a result of which the light scattering is intensified.

In a further development of the invention, the packaging is an endless packaging. The endless packaging is, for example, guided in one piece past the line sensor and then, for example, separated. Thanks to the endless packaging, it can be fed past the line sensor evenly without interruptions.

In a further development of the invention, the line sensor detects a contrast edge in a third area, the position of the first area in relation to the third area being determined since the contrast edge in the third area is at a constant distance from the weld seam in the first area. The contrasting edge can be, for example, a perforation of the object or the packaging.

In a further development of the invention, the light source emits white light with a wavelength of 400 nm to 700 nm. This makes it possible to shine through colored objects without the luminosity being significantly attenuated. For example, if only red light were used, when using an object with the complementary color to red, the wavelength used could be significantly attenuated, which would significantly impair the luminosity. By using white light, objects of different colors can be used and checked.

In a further development of the invention, the light source is a homogeneous linear light source, the light source having a row arrangement of light-emitting diodes. The line-shaped light source is arranged at a distance from the line sensor in parallel. For example, a plurality, for example at least ten or at least 20, light-emitting diodes are arranged in a linear row. However, several parallel rows of light-emitting diodes can also be arranged in order to form a linear or elongated light source. The light-emitting diodes are arranged in a row, for example in a grid of 1 mm to 5 mm, in particular in a grid of 2 mm to 4 mm. The optical axes of the light-emitting diodes are preferably aligned parallel to one another.

Optionally, a diffuse front pane is arranged in front of the light-emitting diodes. The diffuse front panel homogenizes the light, creating a uniform illumination from the light source. The front pane can be made of transparent or partially transparent plastic or glass. For example, the inner surface of the front pane is made diffuse so that the rays pass through the material in an undirected manner, for example by means of a surface treatment such as sandblasting, and the outside of the front pane is smooth, which simplifies cleaning of the front pane.

In a further development of the invention, the light source and the line sensor are electrically synchronized. As a result, the light source and the line sensor can be activated synchronously by the control and evaluation unit and operated synchronously. The light source and the line sensor are only activated for a short recording time of, for example, 2 to 600 microseconds. This reduces self-heating and, if necessary, higher light outputs can be made possible in pulse mode. Furthermore, the pulsed operation of the light source reduces the line sensor's sensitivity to extraneous light, since the control and evaluation unit knows the time and duration of the light pulses, since the light source is controlled by the control and evaluation unit.

In a further development of the invention, the line sensor has a scanning range of 20 mm to 30 mm or 90 to 110 mm. As a result, the line sensor can be mounted at a distance from the object. The scanning range covers tolerances in the positioning of the object.

In a further development of the invention, the line sensor has a field of view of 25 mm to 50 mm. This allows a wide area of 25 mm to 50 mm of the object to be checked, which means that fluctuations in movement or tolerances in the position of the weld seam are harmless. Adjustment of the sensor is further simplified as a result, since alignment is tolerant.

In a further development of the invention, the recording frequency of the line sensor is 500 Hz to 5000 Hz. As a result, the line sensor can be adapted to different object speeds or also to different activation times of the light source.

In a further development of the invention, a multiple exposure and an evaluation of the multiple exposure are carried out by the control and evaluation unit, the multiple exposures being averaged or a histogram being formed.

By averaging the received values of the individual receiving elements of the Line sensor, more precise measured values or more precise light intensities can be determined. As a result, measured values from the first area and the second area can also be compared with very small differences in brightness.

In a histogram evaluation, frequencies with similar reception values of the respective individual reception elements of the line sensor are determined and these frequency values are evaluated in order to determine more precise measured values or more precise light intensities. As a result, measured values from the first area and the second area can also be compared with very small differences in brightness.

In a further development of the invention, the line sensor is used for continuous monitoring, the object being moved past the line sensor by a transport device, the speed being 0.1 m / s to 4 m / s. As a result, a large number of object sections or packaging sections can first be checked in a short time and, secondly, a large number of scanning processes can be carried out within an object section or a packaging section in order to obtain reliable detection or detection of the weld seam.

In a further development of the invention, the control and evaluation unit is designed to continuously output a binary switching signal, the switching signal indicating whether the weld seam is present or not. This enables automated continuous control of the manufacturing process and checking of the weld seam. For example, the production process can be stopped automatically if there is no longer a weld seam in the object or the packaging. A display can also be coupled to the binary switching signal, which visually indicates whether a weld seam is present or not. As a result, an operator of the machine can manually influence the production process and make the point in time for an intervention dependent on the situation.

• 1 bis 3 jeweils eine erfindungsgemäße Vorrichtung mit einem Zeilensensor;
• 4 und 5 jeweils ein Diagramm mit einem Helligkeitsverlauf;
• 6 bis 8 jeweils ein Objekt bzw. eine Verpackung.

In the following, the invention will also be explained with regard to further advantages and features with reference to the accompanying drawings using exemplary embodiments. The figures of the drawing show in:

• 1 to 3 each a device according to the invention with a line sensor;
• 4th and 5 each a diagram with a brightness curve;
• 6th to 8th one object or one packaging.

In the following figures, identical parts are provided with identical reference symbols.

1 shows an apparatus 1 with a line sensor 2 and a light source 3 and an object 4th which is partially transparent, with the object 4th between the line sensor 2 and the light source 3 is arranged, the light rays from the light source 3 the object 4th partially penetrate and hit the line sensor 2 hit, the line sensor 2 a control and evaluation unit 6th having, the object 4th is made of plastic, the object being 4th at least two parallel plastic films 7th , 8th having, the object 4th a weld seam in at least one area 9 has, whereby the two plastic films 7th , 8th are cohesively connected, the light at least in a first area 10 of the property 4th with the weld 9 and at least in a second area 11 of the property 4th without weld seam 9 is recorded, the control and evaluation unit 6th the one from the line sensor 2 detected light intensity of the first area 10 and the second area 11 compares with each other, the weld 9 thereby from the control and evaluation unit 6th what is detected is that the detected light intensity, that is to say the transmission in the first area 10 is higher than the second area 11 .

By the line sensor 2 with a plurality of receiving elements in a row or row, there are also several receiving elements in the first area 10 and the second area 11 evaluated. The brightness values or light intensity values of the respective individual receiving elements in the first area 10 and the second area 11 can for example be averaged in order to obtain an average luminous intensity value for each area.

The line sensor 2 is, for example, transverse to the weld seam 9 arranged. Here are the optical axes of the line sensor 2 also across the weld 9 arranged.

The line sensor 2 is for example according to 1 together with the control and evaluation unit 6th arranged in a first housing. Next is the light source 3 arranged in a second housing which is arranged at a distance from the first housing.

The line sensor 2 is an optoelectronic sensor for the optical, contactless detection of objects.

According to 6th is the object 4th a packaging 5 , with the packaging 5 in the first and second area made of light and white plastic film 7th is. The plastic film 7th is therefore more translucent, which means that a weaker light source is used can be. According to 6th is only the surface of a single plastic film 7th shown.

According to 6th shows the plastic film 7th an air cushion, the surface being an uneven and uneven surface. 6th shows the packaging 5 without weld seam 9 .

In the arrangement with transmitted light, there is no use of reflection in this system. Even when the light emerges from the plastic film 7th an excessive directed light extraction is avoided. The plastic film 7th thereby forms an optical diffuser which forms diffusely scattered light. For example, the plastic film 7th a matt, matt or partially matt surface on the outer surface, which intensifies the light scattering.

According to 3 is the packaging 5 an endless packaging 13th . The endless packaging 13th becomes, for example, one piece on the line sensor 2 passed and then, for example, sporadically.

According to 3 the line sensor detects 2 a contrasting edge 14th in a third area 15th , where the position or the distance of the first area 10 to the third area 15th is determined as the contrasting edge 14th in the third area 15th a constant distance to the weld seam 9 in the first area 10 having. At the contrasting edge 14th For example, it can be a perforation of the object 4th or the packaging 5 act.

According to 2 sends the light source 3 emits white light with a wavelength of 400 nm to 700 nm. This means that colored objects are also possible 4th to shine through without the luminosity being significantly attenuated. By using white light, objects of different colors can be created 4th used and checked.

According to 2 is the light source 3 a homogeneous linear light source 3 , being the light source 3 has a series arrangement of light emitting diodes. The linear light source 3 is spaced parallel to the line sensor 2 arranged. For example, a plurality, for example at least ten or at least twenty, light-emitting diodes are arranged in a linear row. However, several parallel rows of light-emitting diodes can also be arranged around a linear or elongated light source 3 to build. The light-emitting diodes are arranged in a row, for example in a grid of 1 mm to 5 mm, in particular in a grid of 2 mm to 4 mm. The optical axes of the light-emitting diodes are preferably aligned parallel to one another.

According to 2 a diffuse front panel is arranged in front of the light-emitting diodes. The diffuse front panel homogenizes the light, creating a uniform illumination from the light source. The front pane can be made of transparent or partially transparent plastic or glass. In this case, for example, the inner surface of the front pane is made diffuse, for example by means of a surface treatment such as sandblasting, and the outside of the front pane is smooth, which simplifies cleaning of the front pane.

According to 2 are the light source 3 and the line sensor 2 electrically synchronized. This allows the light source 3 and the line sensor 2 through the control and evaluation unit 6th activated synchronously and operated synchronously. The light source 3 and the line sensor 2 are only activated for a short recording time of, for example, 2 to 600 microseconds.

According to 2 indicates the line sensor 2 a range of 20 mm to 30 mm or 90 to 110 mm. This allows the line sensor 2 spaced from the object 4th to be assembled.

According to 2 indicates the line sensor 2 a field of view of 25 mm to 50 mm. This allows a wide area from 25 mm to 50 mm of the object 4th checked, creating fluctuations in movement or tolerances in the position of the weld 9 are harmless.

For example, the recording frequency of the line sensor is 500 Hz to 5000 Hz.

According to 3 there is a multiple recording and an evaluation of the multiple recording by the control and evaluation unit 6th , whereby the multiple recordings are averaged or a histogram is formed.

By averaging the received values of the respective individual receiving elements of the line sensor 2 more precise measured values or more precise light intensities can be determined. As a result, it is also possible to compare measured values from the first area 10 and the second area 11 can be carried out with very small differences in brightness.

In the case of a histogram evaluation, frequencies with similar reception values of the respective individual reception elements of the line sensor are determined 2 and these frequency values are evaluated in order to determine more precise measured values or more precise light intensities. As a result, it is also possible to compare measured values from the first area 10 and the second area 11 can be carried out with very small differences in brightness.

According to 3 takes place with the line sensor 2 continuous monitoring, the object 4th by a transport device 18th on the line sensor 2 is moved past, the speed is 0.1 m / s to 4 m / s.

According to 3 is the control and evaluation unit 6th designed to continuously output a binary switching signal, the switching signal indicating whether the weld seam 9 is present or not. For example, a display can also be coupled to the binary switching signal, which visually indicates whether a weld seam is being welded 9 is present or not.

4th shows a diagram with a brightness curve of the line sensor 2 according to 2 without a weld 9 but with a perforation. The X-axis corresponds to a length extension of the detection area of the line sensor 2 with line pixels or receiving elements. The received positions of the receiving elements of the line sensor are thus along the X axis 2 recorded. The received light intensity is on the Y-axis LS of the line sensor 2 applied per receiving element. 4th shows a detected or recorded brightness with the light source switched on 3 or lighting and an object 4th or packaging 5 according to 2 . There is a contrasting edge at position 150 14th recognizable which through the perforation 19th arises.

5 FIG. 11 shows a diagram with a brightness curve of the line sensor according to FIG 2 or according to 3 , with a recorded weld seam 9 and a detected perforation 19th . 5 shows a detected or recorded brightness with the light source switched on 3 or lighting and an object 4th or packaging 5 according to 3 . There is a contrast edge at position or receiving element 150 14th recognizable which through the perforation 19th arises. In the case of position or receiving element 70 to 120, there is an increased brightness or increased light intensity 4th has been determined which by the weld 9 was caused.

According to 7th shows the plastic film 7th an air cushion, the surface being an uneven and uneven surface. According to 7th is a weld 9 in a first area 10 available. 7th shows a front of the package 5 . In the first area 10 the weld 9 the air cushioning is partially destroyed by the plastic welding process, as a result of which the transmission in the first area is increased, as a result of which the difference in brightness differences is increased.

8th shows a back of the packaging 5 out 7th .

List of reference symbols

1

contraption

2

Line sensor

3

Light source

4th

object

5

packaging

6th

Control and evaluation unit

7, 8

Plastic film

9

Weld

10

first area

11

second area

12th

Air cushioning

13th

Endless packaging

14th

Contrast edge

15th

third area

18th

Transport device

19th

perforation

20th

Receiving elements

LS

Light intensity

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102009012558 A1 [0002]
• DE 102014220598 A1 [0002]

Claims (14)

Device (1) with a line sensor (2) and a light source (3) and an object (4) which is partially transparent, the object (4) being arranged between the line sensor (2) and the light source (3), the Light beams from the light source (3) partially penetrate the object (4) and strike the line sensor, the line sensor (2) having a control and evaluation unit (6), characterized in that the object (4) is made of plastic, wherein the object (4) has at least two parallel plastic films (7, 8), the object (4) having a weld seam (9) in at least one area, whereby the two plastic films (7, 8) are materially connected, with the light at least is recorded in a first area (10) of the object (4) with the weld seam (9) and at least in a second area (11) of the object (4) without a weld seam (9), the control and evaluation unit (6) the the light intensity of the first recorded by the line sensor (2) Area (10) and the second area (11) are compared with each other, the weld seam (9) being detected by the control and evaluation unit (6) in that the detected light intensity in the first area (10) is higher than in the second Area (11). Device (1) according to Claim 1 , characterized in that the object (4) is a packaging (5), the packaging (5) in the first area (10) and second area (11) being made of light and white plastic film (7, 8). Device (1) according to Claim 2 , characterized in that the plastic film (7, 8) has an air cushion, the surface of the plastic film (7, 8) being an uneven and uneven surface. Device (1) according to at least one of the preceding Claims 2 to 3 , characterized in that the packaging (5) is an endless packaging (13). Device (1) according to at least one of the preceding claims, characterized in that the line sensor (2) detects a contrast edge (14) in a third area (15), the position or the distance of the first area (10) to the third area (15) is determined because the contrasting edge (14) in the third area (15) is at a constant distance from the weld seam (9) in the first area. Device (1) according to at least one of the preceding claims, characterized in that the light source (3) emits white light with a wavelength of 400 nm to 700 nm. Device (1) according to at least one of the preceding claims, characterized in that the light source (3) is a homogeneous linear light source (3), the light source (3) having a series arrangement of light-emitting diodes. Device (1) according to at least one of the preceding claims, characterized in that the light source (3) and the line sensor (2) are electrically synchronized. Device (1) according to at least one of the preceding claims, characterized in that the line sensor (2) has a range of 20 mm to 30 mm or 90 to 110 mm. Device (1) according to at least one of the preceding claims, characterized in that the line sensor (2) has a field of view of 25 mm to 50 mm. Device (1) according to at least one of the preceding claims, characterized in that the recording frequency of the line sensor (2) is 500 Hz to 5000 Hz. Device (1) according to at least one of the preceding claims, characterized in that a multiple exposure takes place and an evaluation of the multiple exposure is carried out by the control and evaluation unit (6), the multiple exposures being averaged or a histogram being formed. Device (1) according to at least one of the preceding claims, characterized in that continuous monitoring takes place with the line sensor (2), the object (4) being moved past the line sensor (2) by a transport device (18), the speed being 0.1 m / s to 4 m / s. Device (1) according to at least one of the preceding claims, characterized in that the control and evaluation unit (6) is designed to continuously output a binary switching signal, the switching signal indicating whether the weld seam (9) is present or not.

Images