FR3140427A1 - System for measuring the flatness of a substrate - Google Patents

Abstract

The present invention relates to a system for measuring the flatness (1) of a surface, said surface being the surface of a substrate (2) held by a support, said system for measuring flatness comprising a detector module (10) and a light source (12), said light source generating a light beam (F) and being arranged to be fixed on the surface of the substrate or on the support to serve as a reference, said detector module comprises a receiving surface (102) carried by a sensor (102') and able to be placed opposite the light source to be pointed by said light beam and provide an electrical signal representative of the pointed position of the detection surface, characterized in that said detector module is arranged to that the photoelectric sensor is mounted movable orthogonally relative to the plane of the substrate. Figure 1

Description

System for measuring the flatness of a substrate

A system for measuring the flatness of a substrate is provided.

Prior art

The production of a substrate such as flat float glass consists of pouring molten glass onto a bath of liquid tin which spreads there forming a continuous ribbon. This continuous ribbon is cooled then cut to form plates, preferably rectangular.

A quality criterion for these plates is their flatness. We understand from this that the expected product must present as flat a profile as possible.

However, the glass manufacturing process and, possibly, the treatment process(es), for example thermal treatment of the plates, are likely to result in non-flatness of said plates. Indeed, the hot glass leaving the oven and conveyed by roller-type conveying means is likely to deform when it cools.

If the processes are configured and arranged to avoid as much as possible the formation of deformations and undulations of the profile of the glass substrate, these deformations and undulations can still occur.

There is therefore a need to have a system for measuring the flatness of a substrate in order to avoid any quality problems in particular on the transformation stages which follow the float process in particular during the cutting of the glass, its lamination of the glass , or even the creation of double glazing.

The present invention aims to provide a system for measuring the flatness of a substrate which is reliable and precise, i.e. capable of detecting small surface variations.

As such, the invention relates to a system for measuring the flatness of a surface, said surface being the surface of a substrate held by a support, said system for measuring flatness comprising a detector module and a light source, said light source generating a light beam and being arranged to be fixed on the surface of the substrate or on the support to serve as a reference, said detector module comprises a receiving surface carried by a sensor and capable of being placed opposite the light source for be pointed by said light beam and provide an electrical signal representative of the pointed position of the detection surface, characterized in that said detector module is arranged so that the photoelectric sensor is mounted movable orthogonally relative to the plane of the substrate.

According to one example, the photoelectric sensor comprises a PN junction.

According to one example, the PN junction is of the PIN type.

According to one example, layer I has a higher resistivity than layers P and N, layer P comprising two electrodes.

According to one example, the detector module comprises means for guiding the photoelectric sensor and a contact element allowing said photoelectric sensor to be in contact with the surface of the substrate.

According to one example, the guide means further comprise at least one spring element making it possible to ensure contact between the photoelectric sensor and the substrate.

According to one example, the detector module and/or the light source further comprise positioning means.

According to one example, the guiding means further comprise means for adjusting the position of the receiving surface relative to the light beam.

According to one example, at least the detector module is mounted on a movement module.

• Se munir d’un substrat sur un support ;
• Se munir d’un système de mesure de la planéité ;
• Placer la source lumineuse sur le support ou le substrat et le module détecteur sur le substrat et orienter le faisceau lumineux vers la surface réceptrice, ledit module détecteur étant apte à générer un signal électrique représentatif de la position pointée de la surface de détection

The invention further relates to a method for measuring the flatness of a substrate placed on a support, said method comprising the system according to one of the preceding claims and comprising the steps:

• Provide a substrate on a support;
• Equip yourself with a flatness measurement system;
• Place the light source on the support or the substrate and the detector module on the substrate and direct the light beam towards the receiving surface, said detector module being capable of generating an electrical signal representative of the pointed position of the detection surface

Move the detector module relative to the light source while keeping the light source oriented towards the receiving surface to obtain the variation of the position of the light beam on the receiving surface. According to one example, the system comprises guiding means further comprising means for adjusting the position of the receiving surface relative to the light beam and in that said method comprises an adjustment step making it possible to align the beam and the receiving surface with respect to a reference point.

According to one example, at least the detector module is mounted on a movement module, said movement module being activated to obtain the variation of the position of the light beam on the receiving surface

Description of figures

Other particularities and advantages will clearly emerge from the description given below, for information only and in no way limiting, with reference to the appended drawings, in which:

- there represents a schematic representation of a substrate on a support and a flatness measurement system according to the invention;

- there represents a schematic representation of a light source of a flatness measuring system according to the invention;

- there represents a schematic representation of a detector module of a flatness measuring system according to the invention;

- there represents a schematic representation of a sensor of a detector module of a flatness measuring system according to the invention;

- there represents a schematic representation of the operation of a flatness measuring system according to the invention;

- there represents a schematic representation of a variant of a detector module of a flatness measuring system according to the invention;

Detailed description of the invention

The invention represented on the describes a system 1 for measuring the flatness of a substrate 2. This substrate is a substrate made of any rigid material such as a glass or metallic or plastic substrate.

The flatness measurement system comprising a detector module 10 and a light source 12.

The light source 12 is used to generate a beam F towards the detector module. The light source 12 is preferably a collimated source such as a laser. Such a source is a light source whose radiation is almost parallel.

The light source 12 is arranged to be on the substrate 2 or on a support 3 on which the substrate is placed. The light source 12, visible at the , comprises a light beam generator 120 mounted on a base 122 fixed to the substrate 2 or to the support 3 by a fixing means 124. This fixing means 124 can use a suction cup or a clamp system.

According to an exemplary embodiment, the light source 12 is a source whose wavelength is between 600 and 950nm with a beam whose diameter, preferably a few millimeters, is stable over a distance of 5cm to 7m.

The detector module 10, visible at the , is arranged to be placed opposite the light source. This detector module 10 comprises a chassis 100, capable of being placed on the substrate 2. The detector module 10 further comprises a receiving surface 102 mounted on the chassis. The chassis 100 is clever in that it allows the receiving surface to be mobile. The receiving surface 102 is movable relative to the surface of the substrate 2.

For this, the chassis 100 is designed so that the receiving surface 102 is suspended. The frame 100 comprises guide means 104 such as, for example, a vertical rod 1040 relative to the plane of the substrate on which a support element 1042 is slidably mounted. This support element 1042 is able to carry the receiving surface 102 allowing it to be mobile. The detector module 10 further comprises contact means 106.

These contact means 106, like a pad, are integral with the receiving surface 102 or with the support element 1042 and serve to put said receiving surface 102 in contact with the substrate 2. Indeed, the objective of the contact means 106 is to allow the receiving surface 102 to move via the guide means 104, depending on the flatness of the substrate. Thus, depending on the bumps or hollows that the substrate may present, the receiving surface 102 will move vertically or orthogonally relative to the plane of said substrate.

The receiving surface 102 is carried by a sensor 102' sensitive to light, more particularly to the light beam of the light source.

The sensor 102' is chosen to have a response which varies according to the position of the beam relative to said sensor, more precisely relative to the receiving surface. We understand from this that the sensor generates an electrical signal following exposure to a beam and that this electrical signal varies depending on the relative position of the beam on the receiving surface.

Consequently, given that the sensor 102' is movably mounted on its chassis and that said sensor generates an electrical signal which is a function of the position of the beam on the receiving surface, it therefore becomes possible to measure the flatness.

To generate a signal which is a function of the position of the beam on the receiving surface, the sensor can be presented in different shapes.

A first form consists of having a photoresistive sensor. Such a photoresistive sensor consists of a PN junction on which a resistive layer R is deposited making it possible to have a PIN junction as visible at the . This resistive layer R has two electrodes X1 and X2 while the layer N of the PN junction has a so-called common electrode. The sensor is constructed so that the two electrodes X1, X2 are spaced apart by a distance Lx and the common electrode is arranged equidistant from the two electrodes X1,

Such a photoresistive sensor works on the principle that when a beam of light is pointed at the resistive layer, a current I is generated. To know the position of the beam on the sensor, we then use a formula which makes it possible to determine the position, the distance X _A of the beam relative to the midpoint. This formula is as follows and is based on the principle that the current generated propagates towards the two electrodes X1, X2 with a current Ix1 and Ix2.

The currents Ix2, Ix1 are then processed. For this, the currents Ix1 and Ix2 are converted into voltage then converted into value via an analog-to-digital converter before being sent to a processor for further processing. The voltage conversion means, the analog-to-digital conversion means and the processor can be part of the same calculation unit or can be separated. In this case, the voltage conversion means and the analog-to-digital conversion means are separated from the processor and wireless type communication means such as Bluetooth or wifi are arranged to allow the sending of data. The data processed by the processor makes it possible to determine the distance X _A of the beam relative to the midpoint. This data is stored in internal or external memory and/or sent to display means.

To measure the flatness of the substrate, the invention consists of a method which uses the light source 12 and the detector module 10 previously described. The method thus consists of fixing the light source 12 on the substrate or on the support carrying the substrate. This substrate 3 can be horizontal relative to the ground plane or vertical or inclined.

Then, the detector module 10 is positioned opposite the light source 12 so that the light beam F is able to point at the receiving surface of the photoresistive sensor 102'. The detector module 10 is then moved on the surface of the substrate 2 while keeping the beam pointed at the receiving surface of the photoresistive sensor as visible to the .

This movement of the detector module 10 on the surface of the substrate 2 allows the sensor to move along the guide means 104 via the contact means 106. Consequently, as the laser beam remains stationary but the receiving surface 102 is mobile then the junction point of the beam F and the receiving surface 102 changes position.

Consequently, it is possible to obtain a series of data representative of the flatness of the surface of the substrate 2 in one direction.

To obtain this, it is necessary that the dimensions of the receiving surface 102 are such that the light beam F can move there. For this, the receiving surface 102 may have one or two dimensions whose order of magnitude is at least 5, preferably 10 times greater than the diameter of the light beam and compatible with the amplitude of the deformation to be measured.

In a first variant, the contact means 104 of the detector module further comprise a spring element 1044 as visible at the . This spring element 1044 is arranged between the chassis and the sensor 102'. This arrangement is such that it makes it possible to exert a force on the sensor 102' in the direction of the substrate 2. This force advantageously makes it possible to ensure contact between the sensor 102', via the contact means 106, and the substrate 2. Indeed, if gravity acts when the substrate 2 is positioned horizontally relative to the plane of the ground, said substrate 2 can be positioned vertically or with an inclination, for example when the substrate 2 is placed on an easel. In this case, gravity does not ensure permanent contact. The spring element 1044 is therefore used to guarantee this contact.

In another variant, the detector module 10 and/or the light source 12 are provided with positioning means. These positioning means are an aid for the installation of the detector module 10 and/or the light source 12. Indeed, as the light beam of the light source 12 must be facing the sensor of the detector module 10 and the detector module can move, it becomes necessary to ensure proper alignment. For this, the positioning means comprise at least one positioning element. This positioning element is in the form of a pad or a plate extending from the chassis of the detector module or from the base of the light source. This positioning element extends towards the substrate or the support on which the substrate is placed. This positioning element is then able to come into contact with the support or the substrate, preferably at its edge or side wall, to lock the position of said detector module 10 and/or the light source 12.

Furthermore, in the case of the detector module, these positioning means allow the detector module, when moving it, to keep alignment with the light source.

In another variant, the guide means 104 of the detector module 10 comprise an adjustment means. This adjustment means consists, for example, of a screw system, teeth allowing the translation of the sensor on the guide means. This translation makes it possible to adjust and center the position of the beam relative to the sensor.

Indeed, the method of measuring flatness consists of detecting the light beam on the receiving surface 102 to then observe a position which deviates and measure the amplitude of this deviation.

The amplitude is measured in relation to a reference point Pref. This reference point Pref can be any point or can be midpoint Pm of the receiving surface 102. However, depending on whether the light source 12 is positioned on the substrate 2 or its support 3 and depending on the thickness of the substrate, the light beam F of the light source 12 is not necessarily aligned with the midpoint Pm of the sensor. The adjustment means make it possible, during a preliminary step, to voluntarily modify the position of the sensor to be centered on the midpoint Pm.

In another variation, the detector module 10 can be mounted to move automatically. For this, the detector module 10 is mounted on a movement module. This movement module comprises a rail on which the detector module is placed or an arm mounted on a rail, the arm carrying the detector module. The movement module is fixed to the support or to the ground and allows the movement of the detector module. This movement module has the advantage of having a controllable movement which makes it possible to maintain alignment with the light source. Even more preferably, the movement module is placed on the support and also carries the light source. In this case, the implementation of the flatness measurement system is facilitated.

Of course, the present invention is not limited to the example illustrated but is susceptible to various variants and modifications which will appear to those skilled in the art.

Thus, the sensor of the detector module can be presented in different forms. An alternative form consists of having a receiving surface which is made up of a multitude of sensors as described above. The difference is that here each sensor has dimensions similar to that of the beam diameter. The sensors are thus arranged in a grid form. Therefore, when the light beam points at the receiving surface, at least one sensor generates current. It is thus easy to know the position of this sensor in the grid.

It is also possible for several adjacent sensors to generate current, in which case the sensor generating the largest current is the dominant sensor.

Claims (12)

.System for measuring the flatness (1) of a surface, said surface being the surface of a substrate (2) held by a support, said system for measuring flatness comprising a detector module (10) and a light source (12), said light source generating a light beam (F) and being arranged to be fixed on the surface of the substrate or on the support to serve as a reference, said detector module comprises a receiving surface (102) carried by a sensor (102 ') and able to be placed opposite the light source to be pointed by said light beam and provide an electrical signal representative of the pointed position of the detection surface, characterized in that said detector module is arranged so that the photoelectric sensor is mounted movable orthogonally relative to the plane of the substrate. system for measuring the flatness of a surface according to the preceding claim, in which the photoelectric sensor comprises a PN junction. system for measuring the flatness of a surface according to the preceding claim, in which the PN junction is of the PIN type. system for measuring the flatness of a surface according to the preceding claim, in layer I has a resistivity greater than layers P and N, layer P comprising two electrodes. system for measuring the flatness of a surface according to one of the preceding claims, in which the detector module comprises means for guiding (104) the photoelectric sensor and a contact element (106) allowing said photoelectric sensor to be in contact with the surface of the substrate. system for measuring the flatness of a surface according to the preceding claim, in which the guide means further comprise at least one spring element (1044) making it possible to ensure contact between the photoelectric sensor and the substrate. system for measuring the flatness of a surface according to one of the preceding claims, in which the detector module and/or the light source further comprise positioning means. system for measuring the flatness of a surface according to one of the preceding claims, in which the guiding means further comprise means for adjusting the position of the receiving surface relative to the light beam. system for measuring the flatness of a surface according to one of the preceding claims, in which at least the detector module is mounted on a movement module. method of measuring the flatness of a substrate placed on a support, said method comprising the system according to one of the preceding claims and comprising the steps:

• Provide a substrate on a support;
• Equip yourself with a flatness measurement system;
• Place the light source on the support or the substrate and the detector module on the substrate and direct the light beam towards the receiving surface, said detector module being capable of generating an electrical signal representative of the pointed position of the detection surface
• Move the detector module relative to the light source while keeping the light source oriented towards the receiving surface to obtain the variation in the position of the light beam on the receiving surface.

measuring method according to the preceding claim, in which the system comprises guiding means further comprising means for adjusting the position of the receiving surface relative to the light beam and in that said method comprises an adjustment step making it possible to align the beam and the receiving surface with respect to a reference point. measuring method according to the preceding claim, in which at least the detector module is mounted on a displacement module, said displacement module being activated to obtain the variation of the position of the light beam on the receiving surface